Braking system for a lift truck
First Claim
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1. A lift truck comprising:
- a first wheel located on a first side of said truck;
a second wheel located on a second side of said truck opposite from said first side;
at least one drive motor for driving said lift truck;
at least one traction motor controller connected for controlling said at least one drive motor for both moving said truck and for braking said truck, said traction motor controller controlling said at least one drive motor to provide all conventional service braking for said truck;
a first brake associated with said first wheel;
a second brake associated with said second wheel;
wherein said first brake applies a first braking force to provide backup braking, said first brake being operable alone;
said second brake applies a second braking force to provide backup braking, said first braking force and said second braking force being unequal to one another; and
a brake control for controlling said first and second brakes in the event of a failure resulting in loss of at least one signal for controlling said first and second brakes.
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Abstract
A braking system for a lift truck performs all service braking using truck traction drive motors. Mechanical, spring applied, electrically released brakes are coupled to wheels on opposite sides of the truck with the mechanical brakes applying unequal braking forces to the wheels. The mechanical brakes perform park braking and, in the event an electrical system problem arises, backup braking as well that can be modulated by an operator of the truck regardless of the operating condition of the truck.
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Citations
24 Claims
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1. A lift truck comprising:
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a first wheel located on a first side of said truck; a second wheel located on a second side of said truck opposite from said first side; at least one drive motor for driving said lift truck; at least one traction motor controller connected for controlling said at least one drive motor for both moving said truck and for braking said truck, said traction motor controller controlling said at least one drive motor to provide all conventional service braking for said truck; a first brake associated with said first wheel; a second brake associated with said second wheel; wherein said first brake applies a first braking force to provide backup braking, said first brake being operable alone; said second brake applies a second braking force to provide backup braking, said first braking force and said second braking force being unequal to one another; and a brake control for controlling said first and second brakes in the event of a failure resulting in loss of at least one signal for controlling said first and second brakes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method for operating a lift truck having first and second wheels located on first and second sides of said truck, respectively, a first brake associated with said first wheel, a second brake associated with said second wheel, an operator controlled service brake request device, a mast assembly along which forks are raised and lowered, and a mast height sensor, said method comprising:
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applying a first backup braking force with said first brake to said first side of said truck; applying a second backup braking force with said second brake to said second side of said truck, said first braking force being unequal to said second braking force and able to be applied alone without said second braking force; generating first and second brake release signals to release said first and second brakes, respectively, when said truck is to be operated; monitoring said first and second brake release signals; and reapplying said first braking force in response to failure to receive either said first or said second brake release signals and said mast assembly being below a staging height. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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Specification