Patent US3854271A successfully refreshed from Google Patents.
US3854271A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Drive mechanisms
Assignee: Ransomes Sims and Jeffries Ltd
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Filing: 1973-03-27
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Granted: 1974-12-17
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Expires: 1993-03-27
Abstract
Abstract A drive mechanism for driving a plurality of independently rotatable members, comprising a plurality of fluid motors each adapted to be connected to a respective one of the rotatable members, a plurality of variable delivery pumps each connected to a respective one of the fluid motors or to a respective group of the motors to supply fluid thereto, a prime mover arranged to drive the pumps, and control means operable to vary simultaneously the rates of delivery of fluid from each of the pumps thereby to vary the speed of rotation of the respective motors or groups of motors while maintaining constant at a preset value the ratio of the rates of delivery of respective pumps. The mechanism can be used in a lawn mower, having traction motors supplied from one pump and motors driving the cutting cylinders supplied from a second pump, the rates of delivery of the pumps being kept in constant proportion to give a constant number of cuts per yard for the lawn mower.
Inventors
- 👤 E Aldred
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:31
CPC Classifications
A; A01; A01D; A01D34/00; A01D34/01; A01D34/412; A01D34/42; A01D34/46; A01D34/47; A01D34/475; A01D34/56; A01D34/60; A01D2101/00
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
148 words
A drive mechanism for driving a plurality of independently rotatable members, comprising a plurality of groups of fluid motors with each group including at least one fluid motor, each fluid motor adapted to be connected to a respective one of the rotatable members, a plurality of variable delivery pumps each connected to a separate group of the fluid motors to supply fluid thereto, each of said pumps having a separate control element for varying the rate of delivery of fluid from the respective pump, a prime mover arranged to drive the pumps, and control means operatively connected to the control elements of the pumps so as to vary simultaneously the rates of delivery of fluid from the pumps thereby to vary the speed of rotation of the respective groups of motors whilst maintaining constant at a pre-set value the ratio of the rates of delivery of respective pumps.
Claim 2
Dependent Claim
148 words
A drive mechanism for driving a plurality of independently rotatable members, comprising a plurality of groups of fluid motors with each group including at least one fluid motor, each fluid motor adapted to be connected to a respective one of the rotatable members, a plurality of variable delivery pumps each connected to a separate group of the fluid motors to supply fluid thereto, each of said pumps having a separate control element for varying the rate of delivery of fluid from the respective pump, a prime mover arranged to drive the pumps, and control means operatively connected to the control elements of the pumps so as to vary simultaneously the rates of delivery of fluid from the pumps thereby to vary the speed of rotation of the respective groups of motors whilst maintaining constant at a pre-set value the ratio of the rates of delivery of respective pumps.
Claim 3
Dependent Claim
34 words
A drive mechanism as claimed in claim 1, in which the control means is adjustable to vary the pre-set value of the ratio of rates of delivery of any selected pair of the pumps.
Claim 4
Dependent Claim
22 words
A drive mechanism as claimed in claim 1, in which the prime mover is adapted to drive the pumps at constant speed.
Claim 5
Dependent Claim
35 words
A drive mechanism as claimed in claim 1, in which at least one of the pumps is arranged to supply fluid to a group of motors connected in series or in parallel to the pump.
Claim 6
Dependent Claim
94 words
A drive mechanism as claimed in claim 1 in which the control element of each of the variable delivery pumps has a displacement of which from a neutral position varies the rate of delivery of fluid in dependence on the degree of displacement, and the control means comprises a main control member and a mechanical linkage between the main control member and the control member of each pump adapted to effect a displacement of the control element of each group in dependence on the displacement from a neutral position of the main control member.
Claim 7
Dependent Claim
106 words
A drive mechanism as claimed in claim 5, in which each pump control element is a rotatable control shaft, the rate of delivery of each pump being proportional to the angular displacement of its control shaft from a neutral position, the main control member is a rotatable shaft, the main control shaft and pump control shafts being rotatable about parallel axes, and the mechanical linkage comprises a lever fixed to each pump control shaft and connected to a corresponding one of a plurality of levers fixed to the main control shaft by means of a rigid link pivotally connected at opposite ends to the two levers.
Claim 8
Dependent Claim
39 words
A drive mechanism as claimed in claim 6, in which the point of pivotal connection of each rigid link to one of the two corresponding levers is variable thereby to vary the effective radius of action of the lever.
Claim 9
Dependent Claim
18 words
A drive mechanism as claimed in claim 1, in which the prime mover is an internal combustion engine.
Claim 10
Dependent Claim
142 words
A lawn mower having a ground-engaging traction member and a rotatable cutting cylinder and a drive mechanism comprising a prime mover, a first fluid motor drivingly connected to the traction member, a second fluid motor drivingly connected to the cutting cylinder, first and second variable-delivery pumps driven by the prime mover and arranged to supply hydraulic fluid to the first and second motors respectively, each of said pumps having a separate control element for varying the rate of delivery of fluid from the respective pump, and control means operatively connected to the control elements of the pumps so as to vary simultaneously the rate of delivery of each pump whilst maintaining constant the ratio of the rates of fluid supply to the first and second motors thereby to keep constant the ratio of speeds of rotation of the cutter and traction member.
Claim 11
Dependent Claim
142 words
A lawn mower having a ground-engaging traction member and a rotatable cutting cylinder and a drive mechanism comprising a prime mover, a first fluid motor drivingly connected to the traction member, a second fluid motor drivingly connected to the cutting cylinder, first and second variable-delivery pumps driven by the prime mover and arranged to supply hydraulic fluid to the first and second motors respectively, each of said pumps having a separate control element for varying the rate of delivery of fluid from the respective pump, and control means operatively connected to the control elements of the pumps so as to vary simultaneously the rate of delivery of each pump whilst maintaining constant the ratio of the rates of fluid supply to the first and second motors thereby to keep constant the ratio of speeds of rotation of the cutter and traction member.
Claim 12
Dependent Claim
32 words
A lawn mower as claimed in claim 9, and including a plurality of cutting cylinders each provided with a fluid motor, the fluid motors being connected in series to the second pump.
Claim 13
Dependent Claim
50 words
A lawn mower as claimed in claim 9, in which there are provided valve means operable to divert the flow of fluid supplied by the second pump from the second motor to the first motor, to give an increased traction speed for transport of the lawn mower between cutting operations.
Claim 14
Dependent Claim
121 words
A lawn mower as claimed in claim 9, in which the control means includes two pedals positioned so that they can be simultaneously engaged respectively by the right and left foot of the driver of the mower, the pedals being interconnected so that movement of either pedal in one direction under pressure of the driver''s foot causes the other pedal to move in the opposite direction, and the pedals being arranged in the control means so that movement of one pedal under pressure of the driver''s foot effects an increase in the rate of delivery of the pumps, whilst movement of the other pedal under pressure of the driver''s foot effects a decrease in the rate of delivery of the pumps.
Claim 15
Dependent Claim
88 words
A lawn mower as claimed in claim 12, in which the arrangement is such that in a neutral position of the pedals the rate of delivery of the pumps is zero, and movement of one pedal, under pressure of the driver''s foot, beyond its neutral position causes the pumps to supply fluid to the motors to drive the lawn mower forwards, whilst movement of the other pedal, under pressure of the driver''s foot, beyond its neutral position, causes the flow of fluid from the pumps to be reversed.
Claim 16
Dependent Claim
93 words
A lawn-mower as claimed in claim 13, in which there is provided a selector device which can be set by the driver to one of four positions, in a first of which the pedals are free to move over their full range of movement, in a second of which one of the pedals is prevented from being moved beyond its neutral position, in a third of which the other pedal is prevented from being moved beyond its neutral position, and in a fourth of which the pedals are held in their neutral position.
Claim 17
Dependent Claim
18 words
A lawn mower as claimed in claim 9, in which the prime mover is an internal combustion engine.
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) | 1977-12-16 | 1978-06-17 | 1978-12-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-16 | 1982-06-17 | 1982-12-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-16 | 1986-06-17 | 1986-12-17 | $7700.00 | Window Closed / Lapsed |