Warm up cycle for a materials handling vehicle

#The present invention relates to a warm up cycle for use in a materials handling vehicle that warms one or more valves in a hydraulic circuit.

#Known materials handling vehicles include a power unit, a mast assembly, and a platform assembly that includes a fork carriage assembly coupled to the mast assembly for vertical movement relative to the power unit. The mast assembly and platform assembly may each include components that are controlled by a hydraulic working fluid, such as pressurized oil. Valves provided within hydraulic fluid circuits associated with the mast and platform assemblies may control the flow of the working fluid to the components for effecting various functions performed by the components, such as raising/lowering, traversing (also known as side shifting), and pivoting of the lift carriage assembly.

#In accordance with a first aspect of the present invention, a method for operating a materials handling vehicle includes activating the materials handling vehicle and performing a warm up cycle. During the warm up cycle, energy is provided to at least one valve within the materials handling vehicle so as to energize the valve without providing a working fluid to the valve. Providing energy to the at least one valve effects a heating of oil located within the at least one valve.

#While the specification concludes with claims particularly pointing out and distinctly claiming the present invention, it is believed that the present invention will be better understood from the following description in conjunction with the accompanying Drawing Figures, in which like reference numerals identify like elements, and wherein:

#FIG. 1 is a side view of a materials handling vehicle constructed in accordance with the present invention;

#FIG. 2 is a perspective view of the vehicle illustrated in FIG. 1;

#In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration, and not by way of limitation, specific preferred embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and that changes may be made without departing from the spirit and scope of the present invention.

#Referring now to the drawings, and particularly to FIGS. 1-5, which illustrate a materials handling vehicle 10 constructed in accordance with the present invention. In the illustrated embodiment, the vehicle 10 comprises a turret stockpicker, such as the turret stockpicker disclosed in U.S. Pat. No. 7,344,000 entitled “ELECTRONICALLY CONTROLLED VALVE FOR A MATERIALS HANDLING VEHICLE,” the entire disclosure of which is hereby incorporated by reference herein. The vehicle 10 includes a power unit 20 (also referred to herein as a first base unit), a platform assembly 30 (also referred to herein as a first carriage assembly) and a load handling assembly 40 (also referred to herein as a second base unit). The power unit 20 includes a power source, such as a battery unit 22, a pair of load wheels 24, see FIG. 5, positioned under the platform assembly 30, a steered wheel 25, see FIG. 4, positioned under the rear 26 of the power unit 20. The vehicle 10 further comprises a mast assembly 28 coupled to the power unit 20 on which the platform assembly 30 moves vertically. The mast assembly 28 comprises a first mast 28a fixedly coupled to the power unit 20, and a second mast 28b movably coupled to the first mast 28a, see FIGS. 4 and 5.

#A mast piston/cylinder unit 50 is provided in the first mast 28a for effecting movement of the second mast 28b and the platform assembly 30 relative to the first mast 28a and the power unit 20, see FIG. 4. It is noted that the load handling assembly 40 is mounted to the platform assembly 30; hence, the load handling assembly 40 moves with the platform assembly 30. The cylinder 50a forming part of the piston/cylinder unit 50 is fixedly coupled to the power unit 20. The piston or ram 50b forming part of the unit 50 is fixedly coupled to the second mast 28b such that movement of the piston 50b effects movement of the second mast 28b relative to the first mast 28a. The piston 50b comprises a pulley 50c on its distal end, which engages a pair of chains 52 and 54. One unit of vertical movement of the piston 50b results in two units of vertical movement of the platform assembly 30. Each chain 52, 54 is fixedly coupled at a first end 52a, 54a to the first mast 28a and coupled at a second end 52b, 54b to the platform assembly 30. Hence, upward movement of the piston 50b relative to the cylinder 50a effects upward movement of the platform assembly 30 via the pulley 50c pushing upwardly against the chains 52, 54. Downward movement of the piston 50b effects downward movement of the platform assembly 30. Movement of the piston 50b also effects movement of the second mast 28b.