US3837449A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Transmission controlled spring applied steering brakes
Assignee: Fiat Allis Europe SpA
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Filing: 1973-05-07
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Granted: 1974-09-24
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Expires: 1993-05-07
Abstract
Abstract The vehicle is provided with a pair of spring applied brakes which are individually controllable through hydraulic actuators acting in opposition to the springs. The brakes are individually controlled by a valve associated with the hydraulic actuators and are automatically, simultaneously applied by operation of brake pressure regulating valves which are biased by the pressure of the hydraulic control system for the forward-reverse clutches of the vehicle transmission. The vehicle brakes are applied by balancing pressure across the piston of the brake actuator. During forward or reverse travel of the vehicle, the pressure on one side of the brake actuator compresses the spring to release the brakes. When low fluid pressure is supplied as when the engine is dead, the brake actuator pressure will drop thereby permitting the springs to apply the brakes. When the engine is running and the hydraulic systems are functioning normally, the brakes are applied by the springs whenever the pressure is balanced on opposite sides of the spring loaded brake actuator. The brake pressure regulator valves cause the pressure to be balanced at reservoir pressure when the biasing pressure from the change speed transmission control drops to a low level as when in neutral or during directional shifts.
Inventors
- 👤 G Drone
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 03:50
CPC Classifications
B; B60; B60T; B60T7/00; B60T7/12; B60T11/00; B60T11/10; B60T11/103; B60T13/00; B60T13/10; B60T13/12; B60T13/22; B60W; B60W10/00; B60W10/02; B60W10/18
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
511 words
In a crawler tractor having a power shift transmission with forward and reverse clutches, right and left final drive sprockets connected to the transmission output through right and left hydraulically controlled steering clutches, respectively, and right and left brakes operatively associated with said right and left sprockets, respectively, hydraulic control means comprising: a first control system for said steering clutches and brakes including right and left brake actuators each having, a cylinder, a piston having a piston rod extending from an end of said cylinder, a first pressure chamber on the rod end of said cylinder, and a second pressure chamber on the opposite end of said cylinder, means connecting said rods to said right and left brakes, respectively, a pair of springs operatively associated with said pistons, respectively, urging the latter in a direction effecting engagement of said brakes, right and left clutch control valves, each having a control element shiftable between clutch engaged and clutch disengaged positions and each having a clutch port, a supply port and a brake port, a pair of conduits operatively connecting said clutch ports of said right and left clutch valves to said right and left clutches, respectively, a reservoir, pump means connected to said reservoir and to each of said supply ports, a first pair of brake actuator conduits connecting said brake ports of said right and left clutch control valves to said first pressure chambers of said right and left bRake actuators, respectively, a second pair of brake actuator conduits interconnecting said brake ports and said second pressure chambers, respectively, a brake pressure regulating valve in each of said second pair of brake actuator conduits having an inlet, a brake actuator port, an outlet connected to said reservoir, a shiftable flow control element having a first position wherein said inlet is blocked and flow in the associated one of said second pair of brake actuator conduits is prevented, a second position wherein said inlet and said brake actuator port are in communication and flow is permitted in said associated one of said second pair of brake actuator conduits, and a third position in which said inlet, brake actuator port and outlet are in communication, and fluid actuator means operable on pressurization to bias said flow control elements toward their first positions, passage means between each of said second pressure chambers and said reservoir and an individually controllable and manually operated brake valve in each of said passage means having an open position wherein said second chambers are connected to said reservoir and a closed position wherein said second chambers are blocked from communication with said reservoir, a second control system for said power shift transmission for establishing forward, reverse and neutral conditions and having a circuit with fluid at a predetermined low pressure when said transmission is in said neutral condition and at a predetermined high pressure when said transmission is in either of said forward and reverse conditions, and conduit means connecting said circuit to said fluid actuator means, whereby said brakes are engaged in said neutral condition of said transmission.
Claim 2
Dependent Claim
511 words
In a crawler tractor having a power shift transmission with forward and reverse clutches, right and left final drive sprockets connected to the transmission output through right and left hydraulically controlled steering clutches, respectively, and right and left brakes operatively associated with said right and left sprockets, respectively, hydraulic control means comprising: a first control system for said steering clutches and brakes including right and left brake actuators each having, a cylinder, a piston having a piston rod extending from an end of said cylinder, a first pressure chamber on the rod end of said cylinder, and a second pressure chamber on the opposite end of said cylinder, means connecting said rods to said right and left brakes, respectively, a pair of springs operatively associated with said pistons, respectively, urging the latter in a direction effecting engagement of said brakes, right and left clutch control valves, each having a control element shiftable between clutch engaged and clutch disengaged positions and each having a clutch port, a supply port and a brake port, a pair of conduits operatively connecting said clutch ports of said right and left clutch valves to said right and left clutches, respectively, a reservoir, pump means connected to said reservoir and to each of said supply ports, a first pair of brake actuator conduits connecting said brake ports of said right and left clutch control valves to said first pressure chambers of said right and left bRake actuators, respectively, a second pair of brake actuator conduits interconnecting said brake ports and said second pressure chambers, respectively, a brake pressure regulating valve in each of said second pair of brake actuator conduits having an inlet, a brake actuator port, an outlet connected to said reservoir, a shiftable flow control element having a first position wherein said inlet is blocked and flow in the associated one of said second pair of brake actuator conduits is prevented, a second position wherein said inlet and said brake actuator port are in communication and flow is permitted in said associated one of said second pair of brake actuator conduits, and a third position in which said inlet, brake actuator port and outlet are in communication, and fluid actuator means operable on pressurization to bias said flow control elements toward their first positions, passage means between each of said second pressure chambers and said reservoir and an individually controllable and manually operated brake valve in each of said passage means having an open position wherein said second chambers are connected to said reservoir and a closed position wherein said second chambers are blocked from communication with said reservoir, a second control system for said power shift transmission for establishing forward, reverse and neutral conditions and having a circuit with fluid at a predetermined low pressure when said transmission is in said neutral condition and at a predetermined high pressure when said transmission is in either of said forward and reverse conditions, and conduit means connecting said circuit to said fluid actuator means, whereby said brakes are engaged in said neutral condition of said transmission.
Claim 3
Dependent Claim
28 words
The control means set forth in claim 1 wherein said springs are disposed in said second chambers, respectively, and are in thrust transmitting engagement with said pistons, respectively.
Claim 4
Dependent Claim
56 words
The control means of claim 1 wherein each of said pistons includes a sealing surface and each of said brake valves includes a sealing face complimentary to and engageable with an associated one of said sealing surfaces which on engagement therewith prevents escape of fluid from the associated one of said second chambers to said reservoir.
Claim 5
Dependent Claim
51 words
The control means of claim 1 wherein a clutch pressure regulator valve is operatively associated with each of said clutch control valves whereby, when the latter''s control element is in its clutch disengaged position, fluid will flow to said brake port when pressure at said clutch port reaches a predetermined value.
Claim 6
Dependent Claim
383 words
In a vehicle having a power shift transmission and a brake, the combination comprising: a first control system for said brake including a brake actuator having a cylinder, a piston in said cylinder having a rod extending from an end of said cylinder and connected to said brake, a first pressure chamber in the rod end of said cylinder and a second pressure chamber in the other end of said cylinder, a reservoir, reservoir passage means interconnecting said second chamber and said reservoir, a manually operable brake valve operatively associated with said reservoir passage means and shiftable between open and closed positions wherein flow in said reservoir passage means is permitted and prevented, respectively, a spring operatively associated with said piston urging the rod thereon to extend from said cylinder to cause said brake to be applied, pump means having an inlet connected to said reservoir and having an outlet, a first brake conduit connecting said outlet to said first pressure chamber, a second brake conduit connected to said outlet and to said second pressure chamber, a brake pressure regulating valve in said second brake conduit including an inlet port, a brake port, a reservoir port connected to said reservoir, a shiftable flow control element having a first position closing sAid inlet port wherein flow in said second brake conduit is prevented, a second position in which flow in said second brake conduit is permitted by way of said inlet port and said brake port, and a third position in which said first and second chambers are connected to said reservoir, and fluid actuator means operable on pressurization to bias said flow control element toward its first position, a second control system for said power shift transmission including a transmission control valve for effecting neutral, forward and reverse conditions of transmission adjustment, and a circuit having a high pressure level when said transmission is in either of its forward and reverse conditions and a low pressure level when said transmission is in its neutral condition, and conduit means connecting said circuit to said fluid actuator means, said brake being applied when said transmission is in its neutral condition and said first pressure chamber being pressurized to a relatively high pressure level when said transmission is in either of its forward or reverse conditions.
Claim 7
Dependent Claim
383 words
In a vehicle having a power shift transmission and a brake, the combination comprising: a first control system for said brake including a brake actuator having a cylinder, a piston in said cylinder having a rod extending from an end of said cylinder and connected to said brake, a first pressure chamber in the rod end of said cylinder and a second pressure chamber in the other end of said cylinder, a reservoir, reservoir passage means interconnecting said second chamber and said reservoir, a manually operable brake valve operatively associated with said reservoir passage means and shiftable between open and closed positions wherein flow in said reservoir passage means is permitted and prevented, respectively, a spring operatively associated with said piston urging the rod thereon to extend from said cylinder to cause said brake to be applied, pump means having an inlet connected to said reservoir and having an outlet, a first brake conduit connecting said outlet to said first pressure chamber, a second brake conduit connected to said outlet and to said second pressure chamber, a brake pressure regulating valve in said second brake conduit including an inlet port, a brake port, a reservoir port connected to said reservoir, a shiftable flow control element having a first position closing sAid inlet port wherein flow in said second brake conduit is prevented, a second position in which flow in said second brake conduit is permitted by way of said inlet port and said brake port, and a third position in which said first and second chambers are connected to said reservoir, and fluid actuator means operable on pressurization to bias said flow control element toward its first position, a second control system for said power shift transmission including a transmission control valve for effecting neutral, forward and reverse conditions of transmission adjustment, and a circuit having a high pressure level when said transmission is in either of its forward and reverse conditions and a low pressure level when said transmission is in its neutral condition, and conduit means connecting said circuit to said fluid actuator means, said brake being applied when said transmission is in its neutral condition and said first pressure chamber being pressurized to a relatively high pressure level when said transmission is in either of its forward or reverse conditions.
Claim 8
Dependent Claim
35 words
The structure of claim 5 wherein said piston includes a sealing surface and said brake valve includes a shiftable flow control member having a complimentary sealing face adapted for sealing engagement with said sealing surface.
Claim 9
Dependent Claim
24 words
The structure of claim 6 wherein said spring is disposed in said second chamber of said actuator in thrust transmitting engagement with said piston.
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) | 1977-09-23 | 1978-03-25 | 1978-09-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-23 | 1982-03-25 | 1982-09-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-23 | 1986-03-25 | 1986-09-24 | $7700.00 | Window Closed / Lapsed |