US 6,260,646 B1Granted

Power-assisted pallet truck

OwnerRaul U. Fernandez, Daniel C. Mullockinventors

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Abstract

A pallet truck for manually transporting loaded pallets is provided with a momentary locomotion means that assists an operator in starting a load moving from a state of rest. The locomotion subsystem is of suitable weight and size to allow the power-assisted pallet truck to be manually operated, and to allow for use of the pallet truck in similar space constraints as manual pallet trucks. In an enhanced embodiment, a governor switch is provided which disables the power-assistance after the load has been accelerated to walking speed in order to protect the motor from use as a full-time locomotion means.

Claims13

Dependent claims

A power-assisted pallet truck for transporting loaded pallets over flat surfaces under the primary power of a single operator, said pallet truck comprising:

one or more load bed forks for lifting and carrying a loaded pallet;
a steering yoke pivotally mounted to said load bed forks, said steering yoke providing mechanical support to one or more steering wheels which contact the surface;
a tow bar attached to said steering yoke, said tow bar being equipped with an operator handle, and said tow bar being mechanically attached to said steering yoke such that an operator can pull and steer the pallet truck using the operator handle;
an energy storage means having an energy output connector, said energy storage means being mounted to said pallet truck such that it travels with the pallet truck;
a motor means for imparting rotational energy to said steering wheels when engaged, said motor means having motor input connector and a mechanical rotational energy output;
a motor control means adapted to selectively and momentarily engage said motor means by conduction of energy from said energy storage means to said motor means responsive to operator-induced acceleration of the pallet truck, further adapted to automatically disengage said motor means responsive to relatively steady velocity of the pallet truck by interruption of energy from said energy storage means to said motor means, said motor control means having a control input connector and a control output connector;
a first energy conduit for communicating energy from said energy storage means output connector to said motor control input connector;
a second energy conduit for communicating energy from said motor control output connector to said motor input connector;
and
a transmission means suitably disposed between said motor means mechanical rotational energy output and said steering wheels such that when the operator momentarily applies force to said operator handle sufficient to accelerate the pallet truck, energy is conducted from the energy storage means to the motor means such that the motor means momentarily drives the steering wheels to assist the operator during acceleration of the loaded pallet, and such that the motor means is disengaged automatically by said motor control means when the pallet truck attains a stable velocity.

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Dependencies are inferred from the claim text.

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Abstract

A power-assisted pallet truck for transporting loaded pallets over flat surfaces under the primary power of a single operator, said pallet truck comprising:

one or more load bed forks for lifting and carrying a loaded pallet;
a steering yoke pivotally mounted to said load bed forks, said steering yoke providing mechanical support to one or more steering wheels which contact the surface;
a tow bar attached to said steering yoke, said tow bar being equipped with an operator handle, and said tow bar being mechanically attached to said steering yoke such that an operator can pull and steer the pallet truck using the operator handle;
an energy storage means having an energy output connector, said energy storage means being mounted to said pallet truck such that it travels with the pallet truck;
a motor means for imparting rotational energy to said steering wheels when engaged, said motor means having motor input connector and a mechanical rotational energy output;
a motor control means adapted to selectively and momentarily engage said motor means by conduction of energy from said energy storage means to said motor means responsive to operator-induced acceleration of the pallet truck, further adapted to automatically disengage said motor means responsive to relatively steady velocity of the pallet truck by interruption of energy from said energy storage means to said motor means, said motor control means having a control input connector and a control output connector;
a first energy conduit for communicating energy from said energy storage means output connector to said motor control input connector;
a second energy conduit for communicating energy from said motor control output connector to said motor input connector;
and
a transmission means suitably disposed between said motor means mechanical rotational energy output and said steering wheels such that when the operator momentarily applies force to said operator handle sufficient to accelerate the pallet truck, energy is conducted from the energy storage means to the motor means such that the motor means momentarily drives the steering wheels to assist the operator during acceleration of the loaded pallet, and such that the motor means is disengaged automatically by said motor control means when the pallet truck attains a stable velocity.

7 more elements