US3924410A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydrostatic transmission control system
Assignee: Eaton Corp
•
Filing: 1974-10-02
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Granted: 1975-12-09
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Expires: 1994-10-02
Abstract
Abstract An improved hydrostatic transmission control system includes two pilot valves which are selectively operable to perform the dual functions of (1) effecting actuation of a main control valve from a neutral position to either one of two actuated positions to port fluid to vary the displacement of the hydrostatic transmission and (2) effecting a change in the rate at which fluid is ported and the displacement of the hydrostatic transmission is varied. When the displacement of the hydrostatic transmission is to be increased, a first one of the pilot valves is actuated to effect operation of the main control valve from the neutral position to a first actuated position in which fluid is ported to a swashplate motor to effect an increase in the displacement of the hydrostatic transmission. If a relatively large increase is to be made in the displacement of the hydrostatic transmission, the second pilot valve is also actuated to increase the rate of fluid flow between the main control valve and the swashplate motor. When the displacement of the hydrostatic transmission is to be decreased, the second pilot valve is actuated to effect operation of the main control valve from the neutral position to a second actuated position in which fluid is ported to the swashplate motor to effect a decrease in the displacement of the hydrostatic transmission. If a relatively large reduction is to be made in the displacement of the hydrostatic transmission, the first pilot valve is also actuated to increase the rate at which fluid is conducted between the main control valve and the swashplate motor. A control circuit for effecting operation of the two pilot valves to either increase or decrease the displacement of the hydrostatic transmission in response to a command signal includes a time delay circuit to effect sequential operation of the two pilot valves when a relatively large change is to be made in the displacement of the hydrostatic transmission.
Inventors
- 👤 Charles R Cornell
- 👤 Dennis D Simpson
- 👤 Kenneth K Knapp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:59
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/42; F16H61/439; F16H61/423; F16H61/433
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
284 words
An apparatus comprising a hydrostatic transmission including a pump unit connected in fluid communication with a motor unit, actuator means for varying the displacement of one of said units, main control valve means for porting fluid to effect operation of said actuator means to vary the displacement of said one unit of said hydrostatic transmission, said main control valve means being operable from a neutral condition to a first condition to effect operation of said actuator means to increase the displacement of said one unit of said hydrostatic transmission and being operable from the neutral condition to a second condition to effect operation of said actuator means to decrease the displacement of said one unit of said hydrostatic transmission, first pilot valve means for effecting operation of said main control valve means from the neutral condition to the first condition and for effecting a variation in the rate at which fluid is ported by said main control valve means independently of said main control valve means when said main control valve means is in the second condition to thereby effect a variation in the rate at which said actuator means decreases the displacement of said one unit of said hydrostatic transmission, and second pilot valve means for effecting operation of said main control valve means from the neutral condition to the second condition and for effecting a variation in the rate at which fluid is ported by said main control valve means independently of said main control valve means when said main control valve means is in the first condition to thereby effect a variation in the rate at which said actuator means increases the displacement of said one unit of said hydrostatic transmission.
Claim 2
Independent Claim
284 words
An apparatus comprising a hydrostatic transmission including a pump unit connected in fluid communication with a motor unit, actuator means for varying the displacement of one of said units, main control valve means for porting fluid to effect operation of said actuator means to vary the displacement of said one unit of said hydrostatic transmission, said main control valve means being operable from a neutral condition to a first condition to effect operation of said actuator means to increase the displacement of said one unit of said hydrostatic transmission and being operable from the neutral condition to a second condition to effect operation of said actuator means to decrease the displacement of said one unit of said hydrostatic transmission, first pilot valve means for effecting operation of said main control valve means from the neutral condition to the first condition and for effecting a variation in the rate at which fluid is ported by said main control valve means independently of said main control valve means when said main control valve means is in the second condition to thereby effect a variation in the rate at which said actuator means decreases the displacement of said one unit of said hydrostatic transmission, and second pilot valve means for effecting operation of said main control valve means from the neutral condition to the second condition and for effecting a variation in the rate at which fluid is ported by said main control valve means independently of said main control valve means when said main control valve means is in the first condition to thereby effect a variation in the rate at which said actuator means increases the displacement of said one unit of said hydrostatic transmission.
Claim 3
Dependent Claim
210 words
An apparatus as set forth in claim 1 further including first passage means for conducting fluid between said actuator means and said first pilot valve means when said main control valve means is in the second condition, said first pilot valve means being operable from a first condition in which a relatively low fluid flow is directed through said first passage means to a second condition in which a relatively High fluid flow is directed through said first passage means to thereby effect a variation in the rate at which fluid is ported by said main control valve means when said main control valve means is in its second condition, second passage means for conducting fluid between said actuator means and said second pilot valve means when said main control valve means is in the first condition, said second pilot valve means being operable from a first condition in which a relatively low fluid flow is directed through said second passage means to a second condition in which a relatively high fluid flow is directed through said second passage means to thereby effect a variation in the rate at which fluid is ported by said main control valve means when said main control valve means is in its first condition.
Claim 4
Dependent Claim
92 words
An apparatus as set forth in claim 2 further including means for preventing operation of said first pilot valve means from its first condition to its second condition for a predetermined time period after initiation of operation of said second pilot valve means from its first condition to its second condition and for preventing operation of said second pilot valve means from its first condition to its second condition for a predetermined time period after initiation of operation of said first pilot valve means from its first condition to its second condition.
Claim 5
Dependent Claim
159 words
An apparatus as set forth in claim 1 further including first means for providing a first electrical signal indicative of the displacement of said one unit, second means for providing a second electrical signal indicative of a selected displacement of said one unit, means for providing an electrical output signal which indicates whether the displacement of said one unit is greater than or less than the selected displacement, means for effecting actuation of said first pilot valve means to effect operation of said main control valve means from the neutral condition to the first condition when said output signal indicates that the displacement of said one unit is less than the selected displacement, and means for effecting actuation of said second pilot valve means to effect operation of said main control valve means from the neutral condition to the second condition when said output signal indicates that the displacement of said one unit is greater than the selected displacement.
Claim 6
Dependent Claim
342 words
An apparatus as set forth in claim 1 further including first means for providing a first electrical signal indicative of the displacement of said one unit, second means for providing a second electrical signal indicative of a selected displacement of said one unit, means for providing a first electrical output signal which indicates whether the displacement of said one unit is less than the selected displacement by an amount which is greater than or less than a first predetermined amount when the displacement of said one unit is less than the selected displacement and for providing a second electrical output signal which indicates whether the displacement of said one unit exceeds the selected displacement by an amount which is greater than or less than a second predetermined amount when the displacement of said one unit exceeds the selected displacement, means for effecting actuation of said first pilot valve means to effect operation of said main control valve means from the neutral condition to the first condition when said first output signal indicates that the displacement of said one unit is less than the selected displacement and for effecting operation of said second pilot valve means to provide a relatively high rate at which fluid is ported by said main control valve means when said first output signal indicates that the displacement of said one unit is less than the selected displacement by an amount which is greater than the first predetermined amount, and means for effecting actuation of said second pilot valve means to effect operation of said main control valve means from the neutral condition to the second condition when said second output signal indicates that the displacement of said one unit exceeds the selected displacement and for effecting operation of said first pilot valve means to provide a relatively high rate at which fluid is ported by said main control valve means when said second output signal indicates that the displacement of said one unit exceeds the selected displacement by an amount which is greater than said second predetermined amount.
Claim 7
Dependent Claim
60 words
An apparatus as set forth in claim 5 further including means for preventing actuation of said second pilot valve means for a predetermined time period after initiation of actuation of said first pilot valve means and for preventing actuation of said first pilot valve means for a predetermined time period after initiation of actuation of said second pilot valve means.
Claim 8
Independent Claim
389 words
An apparatus comprising a hydrostatic transmission including a pump unit connected in fluid communication with a motor unit, actuator means for varying the displacement of one of said units, main control valve means connected in fluid communication with said actuator means for porting fluid to effect operation of said actuator means to vary the displacement of said one unit of said hydrostatic transmission, said main control valve means including a main valve member movable from a neutral position to a first actuated position to port fluid to effect operation of said actuator means to increase the displacement of said one unit and movable from the neutral position to a second actuated position to port fluid to effect operation of said actuator means to decrease the displacement of said one unit, first pilot valve means operable from a first condition to a second condition to effect movement of said main valve member from the neutral position to the first actuated position and to maintain said main valve member in the first activated position until said first pilot valve means is operated from the second condition to the first condition, and second pilot valve means operable from a first condition to a second condition to effect movement of said main valve member from the neutral position to the second actuated position and to maintain said main valve member in the second actuated position until said second pilot valve means is operated from the second condition to the first condition, said first pilot valve means being operable from its first condition to its second condition while said second pilot valve means is in its second condition to effect a variation in the rate at which fluid is ported by said main control valve means to thereby effect a variation in the rate of operation of said actuator means and the rate at which the displacement of said one unit is varied, said second pilot valve means being operable from its first condition to its second condition when said first pilot valve means is in its second condition to effect a variation in the rate at which fluid is ported by said main control valve means to thereby effect a variation in the rate of operation of said actuator means and the rate at which the displacement of said one unit is varied.
Claim 9
Independent Claim
389 words
An apparatus comprising a hydrostatic transmission including a pump unit connected in fluid communication with a motor unit, actuator means for varying the displacement of one of said units, main control valve means connected in fluid communication with said actuator means for porting fluid to effect operation of said actuator means to vary the displacement of said one unit of said hydrostatic transmission, said main control valve means including a main valve member movable from a neutral position to a first actuated position to port fluid to effect operation of said actuator means to increase the displacement of said one unit and movable from the neutral position to a second actuated position to port fluid to effect operation of said actuator means to decrease the displacement of said one unit, first pilot valve means operable from a first condition to a second condition to effect movement of said main valve member from the neutral position to the first actuated position and to maintain said main valve member in the first activated position until said first pilot valve means is operated from the second condition to the first condition, and second pilot valve means operable from a first condition to a second condition to effect movement of said main valve member from the neutral position to the second actuated position and to maintain said main valve member in the second actuated position until said second pilot valve means is operated from the second condition to the first condition, said first pilot valve means being operable from its first condition to its second condition while said second pilot valve means is in its second condition to effect a variation in the rate at which fluid is ported by said main control valve means to thereby effect a variation in the rate of operation of said actuator means and the rate at which the displacement of said one unit is varied, said second pilot valve means being operable from its first condition to its second condition when said first pilot valve means is in its second condition to effect a variation in the rate at which fluid is ported by said main control valve means to thereby effect a variation in the rate of operation of said actuator means and the rate at which the displacement of said one unit is varied.
Claim 10
Dependent Claim
196 words
An apparatus as set forth in claim 7 further including first passage means for conducting fluid between said actuator means and said first pilot valve means when said main valve member is in the second actuated position, said first pilot valve means being effective in its first condition to retard fluid flow through said first passage means and being effective in its second condition to promote fluid flow through said first passage means to thereby effect a variation in the rate at which fluid is ported by said main control valve means when said main valve member is in the second actuated position, second passage means for conducting fluid between said actuator means and said second pilot valve means when said main valve member is in the first actuated position, said second pilot valve means being effective in its first condition to retard fluid flow through said second passage means and being effectiVe in its second condition to promote fluid flow through said second passage means to thereby effect a variation in the rate at which fluid is ported by said main control valve means when said main valve member is in the first actuated position.
Claim 11
Dependent Claim
101 words
An apparatus as set forth in claim 7 further including means for preventing operation of said first pilot valve means for preventing operation of said first pilot valve means from its first condition to its second condition for a predetermined time period after initiation of operation of said second pilot valve means from its first condition to its second condition and for preventing operation of said second pilot valve means from its first condition to its second condition for a predetermined time period after initiation of operation of said first pilot valve means from its first condition to its second condition.
Claim 12
Dependent Claim
378 words
An apparatus as set forth in claim 7 further including first means for providing a first electrical signal indicative of the displacement of said one unit, second means for providing a second electrical signal indicative of a selected displacement of said one unit, means for providing a first electrical output signal which indicates whether the displacement of said one unit is less than the selected displacement by an amount which is greater than or less than a first predetermined amount when the displacement of said one unit is less than the selected displacement and for providing a second electrical output signal which indicates whether the displacement of said one unit exceeds the selected displacement by an amount which is greater than or less than a second predetermined amount when the displacement of said one unit exceeds the selected displacement, means for effecting actuation of said first pilot valve means from its first condition to its second condition to effect movement of said main valve member from the neutral position to the first actuated position when said first output signal indicates that the displacement of said one unit is less than the selected displacement and for effecting actuation of said second pilot valve means from its first condition to its second condition to effect an increase in the rate at which fluid is ported by said main control valve means when said first output signal indicates that the displacement of said one unit is less than the selected displacement by an amount which is greater than the first predetermined amount, and means for effecting actuation of said second pilot valve means from its first condition to its second condition to effect movement of said main valve member from the neutral position to the second actuated position when said second output signal indicates that the displacement of said one unit exceeds the selected displacement and for effecting actuation of said first pilot valve means from its first condition to its second condition to effect an increase in the rate at which fluid is ported by said main control valve means when said second output signal indicates that the displacement of said one unit is greater than the selected displacement by an amount which is greater than said second predetermined amount.
Claim 13
Dependent Claim
207 words
An apparatus as set forth in claim 7 wherein said main valve member has opposite ends, said main control valve means includes first pressure chamber means for holding fluid under pressure and in fluid communication with one end of said main valve member and second pressure chamber means for holding fluid under pressure and in fluid communication with the other end of said main valve member, said apparatus further including first passage means for connecting said first pressure chamber means in fluid communication with said first pilot valve means, and second passage means for connecting said second pressure chamber means in fluid communication with said second pilot valve means, said first pilot valve means being effective to vary the fluid pressure in said first pressure chamber means upon operation of said first pilot valve means from its firsT condition to its second condition to thereby effect movement of said main valve member from said neutral position to said first position, said second pilot valve means being effective to vary the fluid pressure in said second pressure chamber means upon operation of said second pilot valve means from its first condition to thereby effect movement of said main valve member from said neutral position to said second position.
Claim 14
Independent Claim
642 words
An apparatus comprising a hydrostatic transmission including a pump unit connected in fluid communication with a motor unit, actuator means for varying the displacement of one of said units, main control valve means for porting a fluid to effect operation of said actuator means to vary the displacement of said one unit of said hydrostatic transmission, said main control valve means being operable from a neutral condition to a first condition to effect operation of said actuator means to increase the displacement of said one unit of said hydrostatic transmission and being operable from the neutral condition to a second condition to effect operation of said actuator means to decrease the displacement of said one unit of said hydrostatic transmission, first pilot valve means for effecting operation of said main control valve means from the neutral condition to the first condition and for effecting a variation in the rate at which fluid is ported by said main control valve means when said main control valve means is in the second condition to thereby effect a variation in the rate at which said actuator means decreases the displacement of said one unit of said hydrostatic transmission, second pilot valve means for effecting operation of said main control valve means from the neutral condition to the second condition and and for effecting a variation in the rate at which fluid is ported by said main control valve means when said main control valve means is in the first condition to thereby effect a variation in the rate at which said actuator means increases the displacement of said one unit of said hydrostatic transmission, first means for providing a first signal indicative of the displacement of said one unit of the hydrostatic transmission, second means for providing a second signal indicative of a selected displacement of said one unit of said hydrostatic transmission, means for providing an output signal which indicates whether the displacement of said one unit of said hydrostatic transmission is less than the selected displacement by an amount which is greater or less than a first predetermined amount when the displacement of said one unit of said hydrostatic transmission is less than the selected displacement and for providing a second output signal which indicates whether the displacement of said one unit exceeds the selected displacement by an amount which is greater or less than a second predetermined amount when the displacement of said one unit exceeds the selected displacement, means for effecting actuation of said first pilot valve means to effect operation of said main control valve means from the neutral condition to the first condition when said first output signal indicates that the displacement of said one unit is less than the selected displacement and for effecting actuation of said second pilot valve means to effect an increase in the rate at which fluid is ported by said main control valve means when said main control valve means is in the second condition and said first output signal indicates that the displacement of said one unit is less than the selected displacement by an amount which is greater than the first predetermined amount, and means for effecting activation of said second pilot valve means to effect operation of said main control valve means from the neutral condition to the second condition when said second output signal indicates that the displacement of said one unit exceeds the selected displacement and for effecting actuation of said first pilot valve means to effect an increase in the rate at which fluid is pOrted by said main control valve means when said main control valve means is in the second condition and said second output signal indicates that the displacement of said one unit of said hydrostatic transmission is greater than the selected displacement by an amount which is greater than said second predetermined amount.
Claim 15
Independent Claim
642 words
An apparatus comprising a hydrostatic transmission including a pump unit connected in fluid communication with a motor unit, actuator means for varying the displacement of one of said units, main control valve means for porting a fluid to effect operation of said actuator means to vary the displacement of said one unit of said hydrostatic transmission, said main control valve means being operable from a neutral condition to a first condition to effect operation of said actuator means to increase the displacement of said one unit of said hydrostatic transmission and being operable from the neutral condition to a second condition to effect operation of said actuator means to decrease the displacement of said one unit of said hydrostatic transmission, first pilot valve means for effecting operation of said main control valve means from the neutral condition to the first condition and for effecting a variation in the rate at which fluid is ported by said main control valve means when said main control valve means is in the second condition to thereby effect a variation in the rate at which said actuator means decreases the displacement of said one unit of said hydrostatic transmission, second pilot valve means for effecting operation of said main control valve means from the neutral condition to the second condition and and for effecting a variation in the rate at which fluid is ported by said main control valve means when said main control valve means is in the first condition to thereby effect a variation in the rate at which said actuator means increases the displacement of said one unit of said hydrostatic transmission, first means for providing a first signal indicative of the displacement of said one unit of the hydrostatic transmission, second means for providing a second signal indicative of a selected displacement of said one unit of said hydrostatic transmission, means for providing an output signal which indicates whether the displacement of said one unit of said hydrostatic transmission is less than the selected displacement by an amount which is greater or less than a first predetermined amount when the displacement of said one unit of said hydrostatic transmission is less than the selected displacement and for providing a second output signal which indicates whether the displacement of said one unit exceeds the selected displacement by an amount which is greater or less than a second predetermined amount when the displacement of said one unit exceeds the selected displacement, means for effecting actuation of said first pilot valve means to effect operation of said main control valve means from the neutral condition to the first condition when said first output signal indicates that the displacement of said one unit is less than the selected displacement and for effecting actuation of said second pilot valve means to effect an increase in the rate at which fluid is ported by said main control valve means when said main control valve means is in the second condition and said first output signal indicates that the displacement of said one unit is less than the selected displacement by an amount which is greater than the first predetermined amount, and means for effecting activation of said second pilot valve means to effect operation of said main control valve means from the neutral condition to the second condition when said second output signal indicates that the displacement of said one unit exceeds the selected displacement and for effecting actuation of said first pilot valve means to effect an increase in the rate at which fluid is pOrted by said main control valve means when said main control valve means is in the second condition and said second output signal indicates that the displacement of said one unit of said hydrostatic transmission is greater than the selected displacement by an amount which is greater than said second predetermined amount.
Claim 16
Dependent Claim
60 words
An apparatus as set forth in claim 12 further including means for preventing actuation of said second pilot valve means for a predetermined time period after initiation of actuation of said first pilot valve means and for preventing actuation of said first pilot valve means for a predetermined time period after initiation of actuation of said second pilot valve means.
Claim 17
Dependent Claim
100 words
An apparatus as set forth in claim 12 further including detector means for detecting when the displacement of said one unit is closely approaching the selected displacement with said first and second pilot valve means actuated and said main control valve means porting fluid at a relatively high rate, and means for effecting operation of one of said first and second pilot valve means to reduce the rate at which fluid is ported by said main control valve means in response to detection by said detector means that the displacement of said one unit is closely approaching the selected displacement.
Claim 18
Independent Claim
351 words
An apparatus comprising a hydrostatic transmission including a pump unit connected in fluid communication with a motor unit, first actuator means for varying the displacement of said pump unit, first control valve means for porting fluid to effect operation of said first actuator means to vary the displacement of said pump unit of said hydrostatic transmission, said first control valve means being operable from a neutral condition to a first condition to effect operation of said first actuator means to increase the displacement of said pump unit of said hydrostatic transmission and being operable from the neutral condition to a second condition to effect operation of said first actuator means to decrease the displacement of said pump unit of said hydrostatic transmission, a first pilot valve member movable between first and second positions, means for moving said first pilot valve member from said first position to said second position to effect operation of said first control valve means from the neutral condition to the first condition and for moving said first pilot valve member from said first position to said second position to effect a variation in the rate at which fluid is ported by said first control valve means when said first control valve means is in the second condition to thereby effect a variation in the rate at which said first actuator means decreases the displacement of said pump unit of said hydrostatic transmission, a second pilot valve member movable between first and second positions, and means for moving said second pilot valve member from its first position to its second position to effect operation of said first control valve means from the neutral condition to the second condition and for moving said second pilot valve member from its first position to its second position to effect a variation in the rate at which fluid is ported by said first control valve means when said first control valve means is in the first condition to thereby effect a variation in the rate at which said first actuator means increases the displacement of said pump unit of said hydrostatic transmission.
Claim 19
Independent Claim
351 words
An apparatus comprising a hydrostatic transmission including a pump unit connected in fluid communication with a motor unit, first actuator means for varying the displacement of said pump unit, first control valve means for porting fluid to effect operation of said first actuator means to vary the displacement of said pump unit of said hydrostatic transmission, said first control valve means being operable from a neutral condition to a first condition to effect operation of said first actuator means to increase the displacement of said pump unit of said hydrostatic transmission and being operable from the neutral condition to a second condition to effect operation of said first actuator means to decrease the displacement of said pump unit of said hydrostatic transmission, a first pilot valve member movable between first and second positions, means for moving said first pilot valve member from said first position to said second position to effect operation of said first control valve means from the neutral condition to the first condition and for moving said first pilot valve member from said first position to said second position to effect a variation in the rate at which fluid is ported by said first control valve means when said first control valve means is in the second condition to thereby effect a variation in the rate at which said first actuator means decreases the displacement of said pump unit of said hydrostatic transmission, a second pilot valve member movable between first and second positions, and means for moving said second pilot valve member from its first position to its second position to effect operation of said first control valve means from the neutral condition to the second condition and for moving said second pilot valve member from its first position to its second position to effect a variation in the rate at which fluid is ported by said first control valve means when said first control valve means is in the first condition to thereby effect a variation in the rate at which said first actuator means increases the displacement of said pump unit of said hydrostatic transmission.
Claim 20
Dependent Claim
343 words
An apparatus as set forth in claim 15 further including second actuator means for varying the displacement of said motor unit, second control valve means for porting fluid to effect operation of said second actuator means to vary the displacement of said motor unit of said hydrostatic transmission, said second control valve means being operable from a neutral condition to a first condition to effect operation of said second actuator means to increase the displacement of said motor unit of said hydrostatic transmission and being operable from the neutral condition to a second condItion to effect operation of said second actuator means to decrease the displacement of said motor unit of said hydrostatic transmission, a third pilot valve member movable between first and second positions, means for moving said third pilot valve member from its first position to its second position to effect operation of said second control valve means from its neutral condition to its first condition and for moving said third pilot valve member from its first position to its second position to effect a variation in the rate at which fluid is ported by said second control valve means when said second control valve means is in its second condition to thereby effect a variation in the rate at which said second actuator means decreases the displacement of said motor unit of said hydrostatic transmission, a fourth pilot valve member movable between first and second positions and means for moving said fourth pilot valve member from its first position to its second position to effect operation of said second control valve means from its neutral condition to its second condition and for moving said fourth pilot valve member from its first position to its second position to effect a variation in the rate at which fluid is ported by said second control valve means when said second control valve means is in its first condition to thereby effect a variation in the rate at which said second actuator means increases the displacement of said motor unit of said hydrostatic transmission.
Claim 21
Dependent Claim
366 words
An apparatus as set forth in claim 16 further including first passage means for conducting fluid between said first actuator means and said first pilot valve member when said first control valve means is in its second condition, said first pilot valve member being movable from its first position retarding fluid flow through said first passage means to its second position promoting fluid flow through said first passage means to thereby effect a variation in the rate at which fluid is ported by said first control valve means when said first control valve means is in its second condition, second passage means for conducting fluid between said first actuator means and said second pilot valve member when said first control valve means is in its first condition, said second pilot valve member being movable from its first position retarding fluid flow through said second passage means to its second position promoting fluid flow through said second passage means to thereby effect a variation in the rate at which fluid is ported by said first control valve means when said first control valve means is in its first condition, third passage means for conducting fluid between said second actuator means and said third pilot valve member when said second control valve means is in its second condition, said third pilot valve member being movable from its first position retarding fluid flow through said third passage means to its second position promoting fluid flow through said first passage means to thereby effect a variation in the rate at which fluid is ported by said second control valve means when said second control valve means is in its second condition, fourth passage means for conducting fluid between said second actuator means and said fourth pilot valve member when said second control valve means is in its first condition, said fourth pilot valve member being movable from its first position retarding fluid flow through said fourth passage means to its second position promoting fluid flow through said fourth passage means to thereby effect a variation in the rate at which fluid is ported by said second control valve means when said second control valve means is in its first condition.
Claim 22
Dependent Claim
174 words
An apparatus as set forth in claim 17 further including means for preventing movement of said first pilot valve member from its first position to its second position for a predetermined time period after initiation of movement of said second pilot valve member from its first position to its second position and for preventiNg movement of said second pilot valve member from its first position to its second position for a predetermined time period after initiation of movement of said first pilot valve member from its first position to its second position, means for preventing movement of said third pilot valve member from its first position to its second position for a predetermined time period after initiation of operation of said fourth pilot valve member from its first position to its second position and for preventing movement of said fourth pilot valve member from its first position to its second position for a predetermined time period after initiation of operation of said third pilot valve member from its first position to its second position.
Claim 23
Independent Claim
171 words
An apparatus comprising a hydrostatic transmission including a pump unit connected in fluid communication with a motor unit, actuator means operable under the influence of fluid pressure to vary the displacement of one of said units from an initial displacement to a selected operating displacement, a pump for supplying fluid under pressure, a control valve connected in fluid communication with said pump and said actuator means, said control valve being operable between a first condition preventing fluid flow between said pump and said actuator means and a second condition porting fluid under pressure from said pump to said actuator means to effect operation of said actuator means to vary the displacement of said one unit from the initial displacement to the selected operating displacement, and secondary valve means for porting fluid under pressure to effect operation of said actuator means to change the displacement of said one unit from the selected displacement to the initial displacement upon a failure of said pump to supply fluid under pressure to said control valve.
Claim 24
Independent Claim
171 words
An apparatus comprising a hydrostatic transmission including a pump unit connected in fluid communication with a motor unit, actuator means operable under the influence of fluid pressure to vary the displacement of one of said units from an initial displacement to a selected operating displacement, a pump for supplying fluid under pressure, a control valve connected in fluid communication with said pump and said actuator means, said control valve being operable between a first condition preventing fluid flow between said pump and said actuator means and a second condition porting fluid under pressure from said pump to said actuator means to effect operation of said actuator means to vary the displacement of said one unit from the initial displacement to the selected operating displacement, and secondary valve means for porting fluid under pressure to effect operation of said actuator means to change the displacement of said one unit from the selected displacement to the initial displacement upon a failure of said pump to supply fluid under pressure to said control valve.
Claim 25
Dependent Claim
62 words
An apparatus as set forth in claim 19 further including pressure chamber means communicating with said pump for effecting operation of said secondary valve means from a closed condition blocking fluid flow to an open condition enabling fluid to flow from said actuator means through said secondary valve means in response to a failure of said pump to supply fluid under pressure.
Claim 26
Dependent Claim
75 words
An apparatus as set forth in claim 19 wherein said actuator means includes first and second actuators and said apparatus further including first conduit means for conducting fluid from said control valve to said first actuator, and second conduit means for conducting fluid from said second actuator to said control valve, said secondary control valve means being operable to connect said first and second conduit means in fluid communication upon a failure of said pump.
Claim 27
Dependent Claim
224 words
An apparatus as set forth in claim 19 wherein said control valve is operable from said first condition to said second condition to effect operation of said actuator means to increase the displacement of said one unit of said hydrostatic transmission and being operable from said first condition to a third condition to effect operation of said actuator means to decrease the displacement of said one unit of said hydrostatic transmission, said apparatus further including first pilot valve means for effecting operation of said control valve from the first condition to the second condition and for effecting a variation in the rate at which fluid is ported by said control valve independently of said control valve when said control valve is in the third condition to thereby effect a variation in the rate at which said actuator means decreases the displacement of said pump unit of said hydrostatic transmission, and second pilot valve means for effecting operation of said control valve from the first condition to the third condition and for effecting a variation in the rate at which fluid is ported by said control valve independently of said control valve when said control valve is in the second condition to thereby effect a variation in the rate at which said actuator means increases the displacement of said pump unit of said hyDrostatic transmission.
Claim 28
Dependent Claim
174 words
An apparatus as set forth in claim 22 further including first passage means for conducting fluid between said actuator means and said first pilot valve means when said control valve is in the third condition, said first pilot valve means being operable from a first condition retarding fluid flow through said first passage means to a second condition promoting fluid flow through said first passage means to thereby effect a variation in the rate at which fluid is ported by said control valve when said control valve is in its third condition, second passage means for conducting fluid between said actuator means and said second pilot valve means when said control valve is in the second condition, said second pilot valve means being operable from a first condition retarding fluid flow through said second passage means to a second condition promoting fluid flow through said second passage means to thereby effect a variation in the rate at which fluid is ported by said control valve when said control valve is in its second condition.
Claim 29
Dependent Claim
92 words
An apparatus as set forth in claim 23 further including means for preventing operation of said first pilot valve means from its first condition to its second condition for a predetermined time period after initiation of operation of said second pilot valve means from its first condition to its second condition and for preventing operation of said second pilot valve means from its first condition to its second condition for a predetermined time period after initiation of operation of said first pilot valve means from its first condition to its second condition.
Claim 30
Dependent Claim
142 words
An apparatus as set forth in claim 5 wherein said means for effecting actuation of said first pilot valve means further effects operation of said second pilot valve means to provide a relatively low rate at which fluid is ported by said main control valve means when said first output signal indicates that the displacement of said one unit is less than the selected displacement by an amount which is less than said first predetermined amount, and said means for effecting actuation of said second pilot valve means further effects operation of said first pilot valve means to provide a relatively low rate at which fluid is ported by said main control valve means when said second output signal indicates that the displacement of said one unit exceeds the selected displacement by an amount which is less than said second predetermined amount.
Claim 31
Dependent Claim
48 words
An apparatus as set forth in claim 25 wherein said means for effecting actuation of said pilot valve means effects operation of said main control valve means to the neutral condition when said output signals indicate that the displacement of said one unit closely approximates the selected displacement.
Claim 32
Dependent Claim
32 words
An apparatus as set forth in claim 7 wherein said main control valve means blocks fluid flow from said actuator means when said main control valve member is in said neutral position.
Claim 33
Dependent Claim
131 words
An apparatus as set forth in claim 11 further including a reservoir of fluid, pump means for pressurizing said fluid above the pressure of said fluid in said reservoir, third passage means for connecting said first and second pressure chamber means in fluid communication with said pressurized fluid from said pump means, means restricting the flow of fluid through said third passage means, fourth passage means connecting said first pressure chamber means in fluid communication with said reservoir, fifth passage means connecting said second pressure chamber means in fluid communication with said reservoir, and means restricting the flow of fluid through said fourth and fifth passage means to a degree greater than the restriction in said third passage means to retain pressurized fluid in said first and second pressure chamber means.
Claim 34
Dependent Claim
26 words
An apparatus as set forth in claim 7 further including means for manually moving said main valve member to anyone of said main valve members positions.
Claim 35
Dependent Claim
44 words
An apparatus as set forth in claIm 4 further including means for providing an electrical output signal which indicates that the displacement of said one unit is the same as the selected displacement upon the loss of either said first or second electrical signal.
Claim 36
Dependent Claim
36 words
An apparatus as set forth in claim 4 further including means for adjusting said first electrical signal to correspond to said second electrical signal when said displacement of said one unit corresponds to said selected displacement.
Claim 37
Dependent Claim
57 words
An apparatus as set forth in claim 4 further including means to provide an output signal which indicates that said displacement of said one unit is the same as the selected displacement when said first electrical signal closely approximates said second electrical signal to provide a dead zone in the operation of said main control valve means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-08 | 1979-06-09 | 1979-12-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-08 | 1983-06-09 | 1983-12-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-08 | 1987-06-09 | 1987-12-09 | $7700.00 | Window Closed / Lapsed |