All wheel steering system
First Claim
1. A four wheel steering system for a vehicle comprising front and rear pairs of steerable wheels, control means for selecting a plurality of steering modes, said modes including a first mode in which steering of said rear pair of wheels is generally fixed, a second mode in which movement of said rear pair of wheels is generally opposite to that of said front pair, and a third mode in which movement of said rear pair is generally similar to that of said front pair, and locking means for limiting steering of said rear pair of wheels, said locking means being actuated at a predetermined vehicle speed, closed loop position feedback means for controlling the position of said rear pair of steerable wheels, said closed loop feedback means including a command rotary variable inductance transducer and a feedback rotary variable inductance transducer, both the command rotary variable inductance transducer and feedback rotary variable inductance transducer producing output signals, each output signal including a polarity, the polarity of the output signal of the command rotary variable inductance transducer being reversible, a reversal of the polarity of the output signal of the command rotary variable inductance transducer relative to the polarity of the output signal of the feedback rotary variable inductance transducer causing switching of said system between said second and said third modes.
2 Assignments
0 Petitions
Accused Products
Abstract
An all wheel steering system for heavy vehicles such as airport and municipal service vehicles. A rear wheel lockout is provided to ensure safe operation by preventing rear steering above a pre-set vehicle speed. The system can be adjusted so that rear steering range angles can be varied to fit particular applications. The steering control involves the use of a closed loop position feedback circuit in which a change in the relative polarity of the command and feedback RVITs results in switching of the system between various modes.
65 Citations
7 Claims
- 1. A four wheel steering system for a vehicle comprising front and rear pairs of steerable wheels, control means for selecting a plurality of steering modes, said modes including a first mode in which steering of said rear pair of wheels is generally fixed, a second mode in which movement of said rear pair of wheels is generally opposite to that of said front pair, and a third mode in which movement of said rear pair is generally similar to that of said front pair, and locking means for limiting steering of said rear pair of wheels, said locking means being actuated at a predetermined vehicle speed, closed loop position feedback means for controlling the position of said rear pair of steerable wheels, said closed loop feedback means including a command rotary variable inductance transducer and a feedback rotary variable inductance transducer, both the command rotary variable inductance transducer and feedback rotary variable inductance transducer producing output signals, each output signal including a polarity, the polarity of the output signal of the command rotary variable inductance transducer being reversible, a reversal of the polarity of the output signal of the command rotary variable inductance transducer relative to the polarity of the output signal of the feedback rotary variable inductance transducer causing switching of said system between said second and said third modes.
Specification