Multi function single lever control for lift trucks

• US 6,112,612 A
• Filed: 10/16/1995
• Issued: 09/05/2000
• Est. Priority Date: 01/03/1994
• Status: Expired due to Fees

• Current Assignee: CLARK Material Handling Company
• Original Assignee: CLARK Material Handling Company
• Inventors: Jones, William C. Jr., Seksaria, Arun K.
• Primary Examiner(s): FENSTERMACHER, DAVID MORGAN
• Application Number:
  US08/543,734
• Time in Patent Office: 1,786 Days
• Field of Search: 74/471 XY, 180/333, 414/5, 414/662, 414/663, 414/664, 244/234, 244/235, 244/236, 244/237
• US Class Current: 74/471.0XY
• CPC Class Codes: B66F 9/20 Means for actuating or controlling masts, platforms, or forks power take-off from vehicle transmissions, combined with vehicle propulsion systems B60K
• CPC Class Codes: G05G 2009/04714 with orthogonal axes
• CPC Class Codes: G05G 2009/0474 characterised by means converting mechanical movement into electric signals
• CPC Class Codes: G05G 2009/04774 with additional switches or sensors on the handle
• CPC Class Codes: G05G 9/047 the controlling member being movable by hand about orthogonal axes, e.g. joysticks for switches H01H25/04
• CPC Class Codes: Y10T 74/20201 Control moves in two planes

Abstract

A single lever hand control for multiple functions having two distinct axes of movement. In the case of a stand-up, battery powered lift truck having a mast, a carriage with forks raised and lowered on the mast, and the forks side shifted on the carriage, which also can be tilted from vertical, forward or back, the operator stands facing to the side with reference to the direction of travel of the truck. Movement of the control lever right to left from a neutral position relative to the direction the operator is facing controls the forward or reverse direction and the speed of the truck. The mast and carriage operations are controlled by the lever being pushed or pulled by the operator transversely to the direction of travel. The force required to displace the lever in one direction is less than that required in the other consistent with the large muscle groups employed to overcome the respective forces. Movement of the lever is also consistent with the direction of movement being imparted to the particular function being performed consistent with the ergonomics of a stand-up lift truck.

Claims

1. In a powered industrial lift truck having a stand up operator'"'"'s compartment designed to orient the operator relative to the direction of travel for ergonomical use of different muscle groups of the operator'"'"'s body, a first muscle group comprising those that are capable of imparting a rolling motion in a right to left manner relative to the direction the operator is facing to the operator'"'"'s arm and hand in a first "X" direction of the stand up operator'"'"'s compartment corresponding to the direction of travel and a second muscle group comprising those that are capable of imparting to the operator'"'"'s arm and shoulder a push or pull motion in a second "Y" direction corresponding to the direction of the stand up operator'"'"'s compartment that the operator is facing, the improvement comprising:

powered means for propelling the powered industrial lift truck in either the forward or reverse directions at variable speeds;

a mast mounted on the powered industrial lift truck having a lifting and lowering capability for a load carried by the mast;

a multi function single lever operator hand control in the operator'"'"'s compartment having a neutral position and two directions of motion therefrom comprising;

a first pivot axis perpendicular to the "X" direction of operator'"'"'s compartment about which said single lever operator hand control pivots using the first muscle group;

a second pivot axis perpendicular to the "Y" direction of the stand up operator'"'"'s compartment about which said single lever operator hand control pivots using said second muscle group;

and control means responsive to displacement of said single lever operator hand control in either the "X" or "Y" directions from the neutral position against an ergonomic reaction force acting in the "X" direction which is substantially lighter than an ergonomic reaction force acting in the "Y" direction such that the operator'"'"'s first muscle group is ergonomically coordinated to the lighter reaction force while the second muscle group is ergonomically coordinated to the larger reaction force in the "Y" direction whereby the operator can sustain longer periods of operation minimizing operator fatigue.

2. In a powered industrial lift truck as set forth in claim 1 where the operator is standing in the operator'"'"'s compartment facing at an oblique angle to the direction of travel.

3. In a powered industrial lift truck as set forth in claim 1 wherein;

said control means comprises a first shaft pivotable about said first pivot axis;

spring means biasing the first shaft to the neutral position;

said powered means actuated by said first shaft to propel the powered industrial lift truck in either direction;

a second shaft pivotable about said second pivot axis;

a linkage connected to said second shaft for transposing pivotable motion into rectilinear motion; and

valve means operated by said rectilinear motion connected to said linkage controlling the raising and lowering of said mast.

4. In a powered industrial lift truck as set forth in claim 3 wherein;

a first cam is rotated by said first shaft; and

a pair or switches, one actuated by said first cam when rotated in one direction, and the other when said first cam is rotated in an opposite direction for operating said variable speed controller means.

5. In a powered industrial lift truck as set forth in claim 4 wherein;

said second shaft is pivotally supported below said first shaft,

a carrier member fixed on said second shaft,

said linkage pivotally connected to said carrier member on one end and to said valve means on an other end,

said valve means including at least one valve element, a spring biasing said valve element to a neutral position which also returns said hand control to the neutral position.

6. In a powered industrial lift truck having a stand up operator'"'"'s compartment designed to accommodate an operator standing in the stand up operator'"'"'s compartment facing partially sideways in a "Y" direction laterally to the direction of travel of the powered industrial lift truck in either forward or reverse traveling in an "X" direction of the operator'"'"'s compartment generally perpendicular to the "Y" direction corresponding to either the right or left of the operator;

powered means for propelling the powered industrial lift truck in either the forward or reverse directions at variable speeds;

a mast on the powered industrial lift truck having a lift and lower motion imparted to a load, which motion corresponds to a push, or pull motion of the operator'"'"'s unsupported arm in the "Y" direction of the stand up operator'"'"'s compartment and involving in such push or pull motion, a first larger muscle group for effecting such motion, generally in the direction that the operator is facing, and a first larger resistive force associated with said push or pull motion;

a multi-function single-lever operator hand control having a neutral position and two directions of motion therefrom mounted in said stand-up operator'"'"'s compartment at approximately waist level of the operator, said control comprising;

a first "X" direction of motion corresponding to said "X" direction in the stand up operator'"'"'s compartment which motion corresponds to a right or left rolling motion of the operator'"'"'s unsupported arm and involving in said right or left rolling motion, a smaller muscle group for effecting such motion, generally parallel to the direction the operator is facing, and a second smaller resistive force associated with said rolling motion;

a second "Y" direction of motion;

corresponding to the "Y" direction of the stand up operator'"'"'s compartment;

said first "X" direction of motion comprising a human factors rolling action of the operator'"'"'s hand and unsupported arm for controlling the direction of travel and speed of the powered industrial lift truck;

and;

a control means responsive to displacement of said single-lever hand control from the neutral position in either the "X" or "Y" directions, said control means comprising means rotatable about an axis approximately parallel to the operator'"'"'s unsupported arm and perpendicular to the "X" direction of motion for varying the speed and direction of said powered means operable by the human factors rolling action of the operator'"'"'s hand and unsupported arm as controlled by said second smaller muscle group, and

second means rotatable about an axis generally perpendicular to said first rotational axis being operable by the human factors push or pull action of the operator'"'"'s unsupported arm moving in said "Y" direction of motion involving said first larger muscle group thereby minimizing operator fatigue due to prolonged operation by matching the larger and smaller muscle groups with the larger and smaller resistive forces.

7. In a powered industrial lift truck having a stand up operator'"'"'s compartment as set forth in claim 6, wherein;

said single-lever control pivots on a first axis that extends perpendicular to said "X" direction in the operator'"'"'s compartment in a right or left rolling motion of the operator'"'"'s unsupported arm and said single-lever control independently pivots about a second axis perpendicular to said "Y" direction of the operator'"'"'s compartment in either a push or pull motion of the operator'"'"'s unsupported arm.

8. In a powered industrial lift truck as set forth in claim 7, wherein;

said control means comprises a first shaft rotated by said single-lever hand control on said first axis;

a first cam rotated by said first shaft;

a first pair of switches, one actuated by said first cam when rotated in one direction, the other when said first cam is rotated in an opposite direction;

a variable speed control means varied by rotation of said first shaft in either direction;

a second shaft rotated by said single-lever hand control on a second axis;

a second cam rotated by rotation of said second shaft;

a second pair or switches, one actuated by said second cam when rotated in one direction, the other when the second cam is rotated in the opposite direction.

9. In a powered industrial lift truck as set forth in claim 8, wherein;

said control means includes a selector switch actuated by the operator from the single-lever hand control in the "Y" direction to select different operations of the mast of the truck.

10. In a powered industrial lift truck as set forth in claim 9, wherein;

a plurality of selector switches are arranged in a row on the single-lever hand control positioned so as to be operable by the operator.