Walk along control for pallet truck

Abstract: An improved switch assembly for use with a materials handling truck includes a pair switches that are conveniently placed in a natural position for actuation by an operator while walking along side the truck. The pair of switches are so placed on each side of a steering control handle to prevent inadvertent actuation and therefore inadvertent operation of the truck. One of the pair is operated by the thumb (100) while the other (110) is positioned to be operated by the fingers as the operator grasps the handle. A control circuit responds to the operation of both switches on one side to move the truck forward at a predetermined speed.

Description: Background of the Invention This invention relates to a control handle and system for controlling the operation of a materials handling truck, particularly by an operator walking along side the truck, and is also related to a corresponding truck itself. A typical rider pallet truck comprises a power unit, a steering control unit and load carrying forks. The power unit contains a steerable wheel, an electric traction motor and an electric storage battery. The power unit also includes a platform onto which the operator may step and ride while controlling the truck. The steering control unit includes a handle which the operator uses to control steering and it also contains operator controls such as twist grips for controlling the direction (forward and reverse) and speed of the truck, a coast control , braking control, controls for raising and lowering the forks, a horn switch and a reversing switch. The load carrying forks extend rearwardly from the power unit and usually have small wheels near the rearmost position to aid in supporting the load. When the truck is moved in one increment over long distances, four or more bays (36 feet or more), the operator will usually step up onto the truck and ride. In modern warehouses, an order picking procedure is usually organized in such a way that the operator follows a unidirectional serpentine route through the storage area, picking up stock in a predetermined sequence in order to maximize productivity. Since it is inefficient for the operator to ride the truck when moving only short distances, the operator will usually place the truck in its coast mode and walk along side, picking up the materials from the storage area and placing thos materials on a pallet on the forks. Control of the truck's steering while either riding or walking is done by using a conventional steering control handle. Some trucks have been provided with a side control switch placed for use by the operator to control forward motion of the truck. In a typical operation, the operator may use the side switch to accelerate the truck to walking speed. When approaching a stopping point, the operator will release the switch and allow the truck to coast while the operator moves to an adjacent rack or shelf to pick up an item and place it on a pallet on the forks. The operator plans the coast of the truck so that the pallet on the forks will stop near the operator's position about the same time the operator is ready to place the item on the pallet. After loading the truck, the operator then again operates the side switch and moves the truck toward the next pick up position. The rate of acceleration and speed of the truck may be controlled by jogging the side switch on and off. The coast distance may be controlled by limiting the truck's travel speed prior to releasing the side switch, and of course the time when the side switch is actually released. Generally, the brakes are not needed during this mode of operation although the truck's brakes are of course available for any emergency. A materials handling truck of the aforementioned kind is also known from US-A-4,716,980. From US-A-5,007,301, which is considered to form the closest prior art in relation to the present invention, there is known a control handle for a walk along materials handling truck comprising a pair of hand grips each one of which being positioned on a respective side of said control handle, wherein each hand grip comprises a first switch actuator positioned on one side of said hand grip so as to be operable by the thumb of an operator walking along side the truck when gripping said hand grip, a second switch actuator positioned on another side of said hand grip so as to be operable by the fingers of an operator walking along side the truck when gripping said hand grip. The switch actuator means on the hand grip of US-A-5,007,301 are provided for the simultaneous actuation of the forks of a lift truck upwardly or downwardly and a driving control device, such that the truck may be advanced in either direction while at the same time the forks are lifted or lowered. No means are provided for preventing any inadvertent movement of the truck upon an inadvertent actuation of the corresponding switch. The truck according to US-A-4,716,980 is provided with safety means, namely a so called dead man brake, which is actuated by a spring biased platform on which the operator normally stands to release the brake. Switch means are provided in order to bypass the dead man brake for advancing the truck in a coast mode. However, there are no means provided for preventing any inadvertent actuation of such switch. In view of the afore mentioned prior art it is the object of the present invention to provide a control handle for a materials handling truck and a corresponding materials handling truck which prevent the truck from being advanced by inadvertently touching or actuating a corresponding switch. This object is achieved by a control handle and a corresponding truck having the features of claims 1 and 5, respectively. Summary of the Invention The control handle according to the present invention comprises an improved side switch for use with a materials handling truck, and particularly to a pair of switches that are conveniently placed in a natural position for the operator while walking along side the truck. In the present invention, a pair of switches are placed on each side on the steering control handle. A pair of switches is used to prevent inadvertent operation of the truck. One switch of said pair is operated by the thumb while the other is positioned to be operated by the fingers as the operator grasps the handle. The steering control unit used in one form of pallet truck includes a handle attached to the outer end of a tiller, the handle itself including a yoke assembly, a central compartment containing severall switches for control of various truck functions, and a pair of twist grips, either one of which may be rotated to control the direction of travel as well as the speed of the truck. The handle may be similar to that described in U.S. patent 3,465,841. Braking of the vehicle is done by positioning the tiller either horizontally or vertically. A control circuit responds to the operation of the side switches to move the truck forward at a predetermined speed. According to one embodiment of the present invention there is provided a control handle for a walk along materials handling truck comprising a U-shaped control handle base member having a cross member and a pair of arms, first and second switches placed on either side of said handle for permitting the operation of the truck by an operator walking along side, on each side of said handle a first switch actuator positioned at the end of said arm to be operated by the thumb as the operator grips said arm, a second switch actuator positioned away from the end of said arm to be operated by the fingers as the operator grips said arm, and control circuit means responsive to the actuation of both switches on one side of said handle to move the truck in its forward direction up to a predetermined speed. The invention further provides a materials handling truck that includes a control handle for permitting the operator to a walk along side the truck and to control the forward travel of movement of the truck, the improvement comprising, means forming a hand grip on each side of the control handle, first and second switches placed on each side of the control handle, a first switch actuator associated with said first switch on each side of the control handle and positioned to be operated by the thumb as the operator grasps said hand grip, a second switch actuator associated with said second switch on each side of the control handle and positioned to be operated by the fingers as the operator grasps said hand grip, and control circuit means responsive to the actuation of both switches on one side of the control handle to move the truck in its forward direction up to a predetermined speed. Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims. Brief Description of the Drawings Fig. 1 is a perspective view of a rider pallet truck of the type incorporating the present invention; Fig. 2 is a perspective view of a control handle incorporating the present invention; Fig. 3 is a plan view showing the operator's hand grasping the control handle and operating the two switches that permit auxiliary control of the truck; Fig. 4 is a plan view of the control handle with portions broken away to show the position of the auxiliary switches; and Fig. 5 is a plan view of the handle with a portion broken away to show the auxiliary switches and switch actuators within the handle. Description of the Preferred Embodiment Referring now to the drawings which illustrate a preferred embodiment of this invention, and particularly to Fig. 1, a typical rider pallet truck 10 includes a power unit 15, a steering control unit 20, and load carrying forks 25. The power unit 15 contains a steerable wheel (not shown), usually located directly under the steering control unit, an electric traction motor (not shown), and an electric storage battery 30. The power unit 15 also includes a platform 35 onto which an operator 40 may step and ride while controlling the truck 10. A rail 42 is provided for the operator to grip while riding on the platform. The steering control unit 20 includes a handle 45 mounted at the end of an arm 50 which the operator uses to control steering and other truck functions. The handle 45 also contains operator controls, such as twist grips 55 for controlling the direction (forward and reverse), a reversing switch 65, switches 70 and 75 for controlling the raising and lowering the forks 25, and a horn switch 80. The load carrying forks 25 extend rearwardly from the power unit 15 and includes small wheels 85 near their rearmost position to aid in supporting a load placed on the forks. Outrigger wheels 90 on the power unit are also provided. The arm 50 is moved from side to side to control the direction of the truck, and it may be moved either horizontal or vertical to apply the brakes. The truck will be reversed should the operator make contact with the switch 65 located at the forward part of the handle 45, as shown in Fig. 2. The direction and speed of the truck is controlled by the position of the twist grips 55. These grips are spring biased to a center neutral position. Rotating either grip forward will cause the truck to move forward at a speed proportional to the amount of rotation. Similarly, rotating the grips toward the rear will cause the truck to move in reverse. When the operator is walking beside the truck, as shown in Fig. 1, the truck may be moved in the forward direction at a predetermined low speed by operation of a side operated pair of switches 100 and 110. There are two sets of side switches, a pair on each side of the handle 45. The handle includes a U-shaped base member 120 including a cross member 125 and a pair of arms 130. A mounting member 135 is carried at the center of said base member 120, and a truck electrical control housing 140 is attached thereto, as shown in Fig. 2. The pair of rotatable handles 55 extend from the ends of the arms 130 to the control housing 140 for controlling the speed and direction of motion of the truck. The mounting member 135 is also connected to the arm 50. The first and second switches 100 and 110 are placed on either side of the handle 45, as shown in more detail in Figs. 4 & 5. Switch 100 includes a switch actuator 102 positioned at the end of the arm 130 to be operated by the thumb as the operator grips the arm. The actuator 102 is pivoted at 103 with one end exposed for operation by the thumb and the other end positioned to operate the switch element 105. Switch 110 includes a second switch actuator 112 positioned away from the end of the arm 130 to be operated by the fingers as the operator grips the arm. Actuator 112 is pivoted at 113 and actuates switch element 115. While not shown, a control circuit responds to the operation of both switches on one side of said handle to cause the truck to move in its forward direction at a predetermined speed. While the form of apparatus herein described constitutes a preferred embodiment of this invention, it is to be understood that the invention is not limited to this precise form of apparatus and that changes may be made therein without departing from the scope of the invention, which is defined in the appended claims.

Claims: A control handle (45) for a walk along materials handling truck (10) comprising a pair of hand grips (130) each one of which being positioned on a respective side of said control handle (45), wherein each hand grip (130) comprises a first switch actuator (102) positioned on one side of said hand grip so as to be operable by the thumb of an operator walking along side the truck (10) when gripping said hand grip, a second switch actuator (112) positioned on another side of said hand grip so as to be operable by the fingers of an operator walking along side the truck when gripping said hand grip (130), characterized by a first switch (100) mounted in each hand grip of said control handle (45) which is operated by a respective said first switch actuator (102) when the operator presses on said first switch actuator (102) with the thumb, a second switch (110) mounted in each hand grip of said control handle (45) which is operated by a respective said second switch actuator (112) when the operator grips the second switch actuator (112) with one or more fingers and control circuit means responsive to the simultaneous actuation of both switches (100, 110) of said hand grip (130) to advance the truck at a predetermined speed. A control handle according to claim 1, characterized by a U-shaped control handle base member having a cross-member (120) and a pair of arms, forming said hand grips (130). A control handle according to claim 2, characterized in that said first switch actuator is positioned towards the outside and the end of said hand grip (130) while said second switch actuator is positioned away from the end of the hand grip (130) and on the inside of said hand grip. A control handle according to claim 2 or 3, characterized in that the free ends of said hand grip are connected by means of additional hand grips and switching elements provided for the operation of a materials handling truck. A materials handling truck that includes a control handle for permitting an operator to walk along side the truck to control the forward travel of movement of the truck, characterized by a control handle according to any of claims 1 to 4.

Inventors: STAMMEN HAROLD A, STAMMEN, HAROLD A.
Applicants: CROWN EQUIP CORP, CROWN EQUIPMENT CORPORATION
Application year: 1992
Main classification: B62D51
IPC codes: B62D51, B62B5