Land vehicles – Wheeled – Extensible
Reexamination Certificate
2001-02-14
2003-01-28
Vanaman, Frank (Department: 3618)
Land vehicles
Wheeled
Extensible
C414S495000
Reexamination Certificate
active
06511080
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fork lift trolley, and more particularly an easily-maneuvered fork lift truck with closely-combined steering wheels, a conveniently disposed hoist device, and a track system for ensuring secure raising and lowering of a pair of forks.
2. Description of Related Art
In many industrial applications, there is a need for a small and relatively inexpensive fork lift trolley with which loads can be easily transported by workers without the need for expensive fork lift trucks which can only be driven by qualified staff. By use of such a trolley, heavy loads can be moved around even confined areas, and the trolley is always available for use as it does not have the batteries of a fork lift truck which need a considerable recharging time.
FIG. 7
shows a prior art fork lift trolley comprising a fixed frame (
60
) with two spaced-apart L-shaped members (
64
) with a pair of pivot wheels (
62
) disposed at a front end thereof, a hoist mechanism (
70
) fitted near to the front of the fixed frame (
60
), a handlebar (
63
) fitted to a top of each L-shaped member (
64
), and a pair of forks (
75
) fitted to the fixed frame (
60
) by a pair of X-shaped braces (
65
) and raised and lowered relative to the fixed frame (
60
) by actuation of the hoist mechanism (
70
). The hoist mechanism (
70
) consists of hydraulic device (
72
) fitted to the front of the fixed frame (
60
) and between the forks (
75
) and the pivot wheels (
62
), a pair of chains (
73
) each with a first end secured to the forks (
75
) and a second end secured to a top end of the fixed frame (
60
), a foot pump (
78
) secured to the bottom front end of the fixed frame (
60
), and a pressure release handle (
79
). To raise the forks (
75
), an operator grasps the handlebar (
63
) with two hands to steady the trolley and then steps on the foot pump (
78
) whereby pressurized oil is fed to the hydraulic device (
72
) whereby a piston (
71
) rises therefrom to urge upward a pulley (
74
) around which the chains (
73
) are reeved, such that the forks (
75
) are pulled up. The operator pulls the pressure release handle (
79
) to release the pressurized oil whereby the piston descends, and accordingly the pulley (
74
) and forks (
75
) descend. The X-shaped braces (
65
) each have a lower first end pivotally secured to the front of the fixed frame (
60
), an upper first end pivotally secured to a front end of the respective fork (
75
), a lower second end slidingly received in a bottom bar of each L-shaped member (
64
), and an upper second end slidingly received in an underside of the respective fork (
75
). The braces (
65
) provide support to the forks (
75
) as they rise and fall. Distal end of the lower bars of the L-shaped members (
64
) each house a non-steering wheel (
66
). When the trolley is maneuvered, the operator grasps with two hands the handle (
63
) and steers the trolley by the pivot wheels (
62
). However, the following drawbacks are found with the cited prior art trolley:
(i) the widely-spaced pivot wheels mean that turning axes of the front end are too far apart, and it is difficult to accurately maneuver the trolley.
(ii) The location of the hydraulic device is too far away from the axes of the pivot wheels, whereby a turning circle of the pivot wheels relative to the center line of the piston limits maneuverability of the trolley.
(iii) The pivot wheels can pivot independently of each other which leads to wheel wobble and difficulty in controlling the direction of the trolley during movement, leading to a danger of collision.
(iv) The pressure release handle is separate to the handlebar and so an operator has to let go of the handlebar with one hand to operate the pressure release handle which is inconvenient and contrary to good ergonomic principles.
(v) The pulley and chains do not have good sliding support and slack occurs between the forks and the fixed frame which leads to wobble as the forks rise and fall whereby loose articles being transported may drop and cause injury, damage, etc.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a fork lift trolley with two closely-spaced pivot wheels to enable travelling direction of the trolley to be controlled well by an operator.
Another object of the present invention is to provide a fork lift trolley with a hydraulic mechanism with a longitudinal center line close to axes of the pivot wheels, whereby the trolley has a good turning circle.
Yet another object of the present invention is to provide a fork lift trolley with a sliding track system to securely control raising and lowering of a ram of the fork lift trolley.
Yet another object of the present invention is to provide a fork lift trolley with a pressure release trigger sited ergonomically within a handle of the trolley.
The fork lift trolley includes a frame with two L-shaped members which are spaced apart, a handle pivoted in two planes to the frame, a pair of closely-spaced and linked pivot wheels, a hydraulic mechanism fitted above the pivot wheels and between the handle and the frame, a hydraulic pump actuable by movement of the handle, a pair of forks connected to the frame and supported by a pair of X-shaped braces mounted on lower bars of the L-shaped members, and a hoist mechanism with two chains connected to the frame and a track system in the forks.
Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 3843147 (1974-10-01), Fredericson
patent: 4366883 (1983-01-01), Reeves
patent: 4655466 (1987-04-01), Hanaoka
patent: 4921385 (1990-05-01), Okuno
patent: 4969794 (1990-11-01), Larsen
patent: 5403024 (1995-04-01), Frketic
patent: 5454625 (1995-10-01), Christensen et al.
patent: 5505578 (1996-04-01), Fuller
patent: 5516128 (1996-05-01), Nakade et al.
patent: 5819338 (1998-10-01), Hession
patent: 5829948 (1998-11-01), Becklund
patent: 6024528 (2000-02-01), Taylor
patent: 679929 (1992-05-01), None
patent: 2652071 (1991-03-01), None
patent: 1-226473 (1989-09-01), None
Kolisch & Hartwell, P.C.
Vanaman Frank
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