Pallet truck tiller arm with angular speed mode adjustment and acceleration control
AssigneeThe Raymond Corporation
InventorsRyan Philip Lindsay, Alan W. Bartels
Life of this patent
Estimating the term…
Abstract
A motorized pallet truck includes an angular indicator on the steering arm mechanism providing an internal controller with an angular position of the steering arm or tiller. The controller applies a brake when the tiller is in either of a substantially vertical or substantially horizontal position, limits the speed of the truck for a predetermined rotational movement from the vertical position, and allows full speed of the vehicle when the tiller arm is pulled into a predefined fast driving arc. The controller further limits the rate of acceleration of the truck when the truck is transitioned between a slow and a fast mode of operation to prevent rapid acceleration in the speed of the truck during the transition.
Claims18
A method for controlling the acceleration of a material handling vehicle transitioning between at least a slow and a fast speed mode of operation to provide a smooth transition between the modes of operation, the method comprising the following steps:
- determining when the vehicle is in the slow speed mode;
- determining whether the vehicle is being driven at a non-zero speed in the slow speed mode;
- calculating a time of operation at the non-zero speed in the slow speed mode;
- limiting the acceleration of the vehicle when the vehicle is transitioned into the fast mode of operation and the calculated time of operation at the non-zero speed in the slow mode exceeds a predetermined minimum time.
A material handling vehicle, comprising:
- a drive system controlled by the operator to drive the material handling vehicle in a selected direction;
- a steering mechanism moveable along an arc to select between at least a slow and a fast mode of operation;
- an operator control for selecting a speed of the vehicle in the selected mode of operation;
- and
- a controller for selectively placing the material handling vehicle in the slow mode or the fast mode of operation based on the angle of the steering mechanism, wherein the controller is further programmed to:
- (i) calculate a time period that the material handling vehicle is moving in the slow mode of operation;
- and
- (ii) limit the acceleration of the material handling vehicle to a predetermined rate of acceleration below a normal rate of acceleration when the time period exceeds a predetermined minimum and the material handling vehicle is moved into the fast mode of operation.
A method for controlling the acceleration of a material handling vehicle having at least a slow speed mode and a fast speed mode of operation to provide a smooth speed transition between the slow speed mode and the fast speed mode of operation, the method comprising the following steps:
- determining whether the vehicle is moving in the slow speed mode of operation;
- limiting the acceleration of the vehicle to a reduced acceleration rate as compared to a normal acceleration rate when the material handling vehicle is transitioned from the slow mode of operation into the fast mode of operation while the vehicle is moving in the slow speed mode of operation;
- maintaining the vehicle at the reduced rate of acceleration for a predetermined period of time;
- and
- returning the acceleration of the vehicle to the normal rate of acceleration after the predetermined period of time has elapsed.
Dependencies are inferred from the claim text.