Land vehicles – Wheeled – Running gear
Reexamination Certificate
2000-09-11
2001-12-04
Dickson, Paul N. (Department: 3618)
Land vehicles
Wheeled
Running gear
C280S103000, C280S093502
Reexamination Certificate
active
06325396
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a steering wheel assembly for a vehicle, and more particularly, to a steering wheel assembly for a vehicle with a zero turning radius (ZTR).
Zero turn radius vehicles, such as lawn mowers and windrowers, have relied on caster wheels and some form of independent control of the drive wheels for steering. Such designs can result in poor directional control when traversing side slopes and can limit the usability of the vehicle. Ackerman-type steering mechanisms provide good directional control, but do not normally allow wheels to be turned through a 180° range. A steering mechanism with Ackerman-type geometry and capable of turning wheels through a 180° range is described by E. Chicurel in “Mechanism and Machine Theory”, Vol. 34 No. 3 April 1999. However, the E. Chicurel mechanism is complex and requires a gear or chain drive mechanical amplifier.
SUMMARY OF THE INVENTION
Accordingly, an object of this invention is to provide a steering mechanism which is capable of turning wheels through a 180° range.
A further object of the invention is to provide such a steering mechanism which has Ackerman-type geometry.
Another object of the invention is to provide such a steering mechanism which does not require a gear or chain drive mechanical amplifier.
These and other objects are achieved by the present invention, wherein a vehicle steering assembly includes steerable wheels mounted on half fork members which are pivotally coupled to the outer ends of an axle member. A rack and pinion assembly is attached to the axle member and has an input shaft for coupling to a steering wheel, and has a laterally movable rack member, with a vertical pivot pin attached at each end thereof. A pair of tie rod members each has an end coupled to the corresponding pivot pin. A pair of rocker arm members each has a first end pivotally coupled to a second end of the corresponding tie rod member, and has a second end pivotally coupled to a corresponding end of the axle beam. A pair of connecting rods each has a first end pivotally coupled to the first end of the corresponding rocker arm, and has a second end which is pivotally coupled to the upper arm of the corresponding half fork member.
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patent: 5964308 (1999-10-01), Miyamoto
Chicurel, “A 180° steering interval mechanism”, Mechanism and Machine Theory 34, 1997.
Deere & Company
Dickson Paul N.
Fleming Faye M.
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