WO1999041186A1

WO1999041186A1 - Portable personnel lift with wheel drive mounted on outriggers

Info

Publication number: WO1999041186A1
Application number: PCT/US1999/002693
Authority: WO
Inventors: Michael D. Ream; David D. White
Original assignee: Upright, Inc.
Priority date: 1998-02-13
Filing date: 1999-02-09
Publication date: 1999-08-19
Also published as: AU2592799A

Abstract

A lightweight, driveable and portable personnel lift (10) is provided having four outriggers (31-34) removably connected to the chassis (20). Two of the outriggers (31-32) carry drive motors (61-62) at their outer ends and the other two outriggers (33-34) carry casters (43, 44) at their outer ends. The lift (10) is driveable with the platform (15) elevated and the outriggers (31-34) attached by energizing the drive motors (61, 62) carried at the outer end of two outriggers (31, 32), and the lift is steered by energizing the two drive motors at different speeds or by energizing one drive motor in the forward direction and the other in the reverse direction. The lift (10) also has a multi-stage mast (11) which carries a work platform (15) protected by a safety cage (12) assembly.

Description

PORTABLE PERSONNEL LIFT WITH WHEEL DRIVE MOUNTED ON OUTRIGGERS

Background and Brief Summary of the Invention

The present invention relates in general to personnel lifts. More particularly, the invention provides a lightweight and portable personnel lift with four readily attach- able outriggers. Each outrigger has a wheel which supports its outermost end and two of the wheels have drive motors attached to the end of the outrigger adjacent the wheels, allowing the lift to be self-propelled and driveable in an elevated position. The lift of the present invention is relatively lightweight, of approximately 800 pounds, has working platform heights of 25 feet and higher above the ground while maintaining a narrow width of approximately 29 inches to allow the lift to pass through normal personnel doorways. Working heights in excess of 50 feet may be achieved with a version of the invention weighing about 1200 pounds and less than 80 inches height in its tilt back position.

It is known in the prior art to use outriggers in conjunction with personnel lifts as shown, for example, in Ream et al U.S. patent 4,657,112 dated April 14, 1987 and owned by the assignee of the present application. The Ream et al patent teaches a personnel lift having outriggers 13 and adjustable ground engaging members 14 to stabilize the lift in its elevated position. That patent does not teach or suggest the use of drive wheels carried at the end of any of the outriggers. Another personnel lift design is shown in U.S. patent application Serial No. 08/787,024 filed January 28, 1997 and owned by the assignee of the present invention. That application teaches a personnel lift having outriggers with adjustable ground engaging members, but does not teach or suggest the use of drive motors and drive wheels carried at the outer end of any of the outriggers. U.S. patent 4,015,686 also teaches a personnel lift with outriggers, but does not teach drive wheels carried by the outriggers.

The prior art also includes personnel lifts which are self-propelled and which use counterweights, but the use of the counterweights substantially increases the weight of the machine to more than twice the weight of the present invention. That particular design also increases the width of the apparatus to approximately 10% greater than the width of the present invention.

The users of personnel lifts are constantly demanding lifts which can pass through ordinary personnel doorways, are lightweight but can operate at ever increasing platform heights safely, and which are driveable. A primary object of the present invention is to provide a portable and driveable, lightweight personnel lift having removable outriggers and drive wheel assemblies carried by the ends of two outriggers, and casters carried at the ends of two other outriggers. Another object of the invention is to provide a portable, self-propelled personnel lift having four removable outriggers and wherein steering is accomplished by the use of 3 drive assemblies at the ends of two outriggers and by the use of differential rotational speeds between the two drive wheels.

A further object of the invention is to provide a portable personnel lift which may be transported by one workman, is capable of passing through an ordinary personnel doorway and, also, has a readily attachable series of outriggers with attached drive assemblies allowing the apparatus to be self-propelled and steered with an elevated platform.

Other objects and advantages of the invention will become apparent from the following description and the drawings wherein:

Brief Descriptions of the Drawings Fig. 1 is a perspective representation of the invention with the outriggers and drive wheels installed;

Fig. 2 is a side elevational view of the apparatus shown in Fig. 1;

Fig. 3 is an exploded, perspective view of the inven- tion, wherein a "clamshell" safety cage is shown and wherein screw jacks are shown in each of the outriggers;

Fig. 4 is a perspective view of the apparatus shown in Fig. 3 with the screw jacks fully elevated;

Fig. 5 is a side elevational view of the apparatus shown in Figs. 3 and 4 with the screw jacks fully elevated; 4

Fig. 6 is a perspective schematic of the apparatus shown in Figs. 3-5, showing all four outriggers;

Fig. 7 is a perspective schematic showing the joystick control for the invention; and Fig. 8 is a perspective view of the apparatus shown in

Figs. 3-5, with the joystick control.

Detailed Description of the Drawings

Referring to Figs. 1 and 2, a portable personnel lift 10 is shown. The lift includes a chassis 20 having forward transport wheels 21 and 22 and a pair of rear transport wheels, only one of which (wheel 23) is visible in Fig. 1. The transport wheels are utilized to move the lift into and out of the work area when the outriggers 31,32,33 and 34 are detached. The lift 10 weighs approximately 800 pounds and can be transported by a single workman and which can be rolled (either standing vertically or in a tilt back position) through a standard personnel doorway having a 30 inch width and 80 inch height.

The lift 10 shown in Figs. 1 and 2 includes a multi- sectional telescopic mast 11 of the type shown in the Ream et al U.S. patent 4,657,112, owned by the assignee of the present invention. U.S. patent 4,657,112 is hereby incorporated by reference as if set forth in full. It is to be understood that the telescopic mast is the preferred type of mast to use in conjunction with the present invention. Working heights of over 50 feet are reachable with the present invention. However, other types of masts, including the cantilevered mast design, as shown in U.S. patent 4,015,686, may also be used in conjunction with the detachable outriggers and drive assemblies of the present inven- tion.

Figs. 1 and 2 show a safety cage 12 having removable rails 12a and 12b to allow entry and egress into the safety cage. Platform 15 supports a workman as the mast 11 is extended upwardly. The preferred form of safety cage is shown as 112 in Figs. 3, 4, 5 and 8. Safety cage 112 is a "clamshell" type safety cage and is shown and claimed in U.S. patent application Serial No. 08/787,024 filed January 28, 1997 and owned by the assignee of the present invention. Application Serial No. 08/787,024 is hereby incorporated by reference as if set forth in full herein. The clamshell safety cage 112 pivots about a horizontal axis shown generally as 119 in Figs. 3, 4, 5 and 8. By rotating the upper portion of cage 112 about axis 119, the workman is able to enter the cage from ground level and stand on platform 115. The embodiment of the invention shown in Figs. 1-5 and 8 is capable of raising the work platform to a height of 25 feet above ground level. Working heights of over 50 feet are attained by using larger masts. The units with larger masts are movable by a single workman and can pass through a personnel door (30" x 80") by being tilted back.

Referring to Figs. 3 and 6, a total of four outriggers, 31,32,33 and 34, are shown, and Fig. 3 shows them detached from chassis 20. Outriggers 31 and 32 are described herein and in the claims as first and second outriggers and carry, respectively, first and second drive wheels 41 and 42, respectively. First and second drive motors 61 and 62 are carried by the outermost ends 31a and 32a of outriggers 31 and 32. Drive motors 61 and 62 are connected through reduction gearing to drive wheels 41 and 42, respectively.

The third and fourth outriggers 33 and 34 are removably connected to chassis 20 and carry third and fourth wheels 43 and 44, respectively, which are preferably casters. Third and fourth wheels 43 and 44 are attachable to the outer ends 33a and 34a of outriggers 33 and 34 by L-shaped brackets 45 which are either pinned or bolted to the outrigger.

The drive wheels 41,42 and motors 61,62 are similarly removable from the outer ends 31a, 32b of outriggers 31,32.

The inner ends of all outriggers are connected in the same fashion to the chassis but for clarity only outriggers 31 and 34 will be described. The inner ends 31b and 34b of outriggers 31 and 34 are inserted into generally C-shaped chassis members 36 and 37 until mounting holes 31c and 34c in the outriggers are aligned with mounting holes 36c and 37c formed in members 36 and 37. When the outrigger mounting holes 31c and 34c are aligned with holes 36c and 37c, retaining pins or bolts are inserted therethrough and the outriggers 31 and 34 are securely attached to the chassis 20.

As a practical matter, the lift 10 shown in Fig. 3 is moved to the job site and into the work area on transport wheels 21-24. The outriggers 31-34 are attached to the chassis prior to the wheels 41-44 being attached to the outriggers. Prior to attaching the wheels 41-44, screw jacks 91-94, carried by outriggers 31-34, respectively, are raised to a height such as shown in Figs. 4 and 5 so that wheels 41- 44 can be applied to the ends of the outriggers, after which the screw jacks 91-94 are raised relative to the outriggers. When the screw jacks 91-94 are raised relative to outriggers 31-34, drive wheels 41,42 and the caster wheels 43,44 contact the ground and transport wheels 21-24 are held off the ground as shown in Fig. 5. As shown in Fig. 5, when the screw jacks 91 and 94 are raised, the lift 10 is supported on the ground by only the first and second drive wheels 41 and 42 and the casters or steering wheels 43 and 44. The lift may then be driven by motors 61 and 62 attached to the first and second drive wheels. The lift 10 may be driven with the platform elevated or lowered. As shown best in Figs. 6 and 8, the outriggers 31-34 form a generally X-shaped pattern.

The lift is steered by operating the drive wheels 41 and 42 at different rotational speeds, or by reversing one of the drive wheels and simultaneously rotating the other drive wheel forwardly. Conventional spring brakes are carried by drive wheels 41 and 42. It is also possible to hold either one of the drive wheels stationary and to operate the other drive wheel either forward or reverse and cause the unit to pivot about the stationary drive wheel. Additionally, one drive wheel can be energized in a forward direction simul- 8

taneously with the second drive wheel being energized in a reverse direction to cause the apparatus to swivel within a relatively small footprint on the ground approximately the size of the stationary footprint formed by the lift with outriggers attached.

In practice, one workman can transport the lift with a pickup truck to a job site, move the lift through personnel doorways to a particular work area and can attach the outriggers singlehandedly . The workman may then enter the safety cage and operate the lift with a joystick 150 (Figs. 7 and 8) mounted on the top rail 112a of the safety cage. The joystick has controls for elevating the mast and for energizing one or both drive wheels. The joystick control 150 is not shown in Figs. 1-6 for clarity. Drive wheel 42 and drive motor 62 are not shown in Fig. 8.

It is to be understood that various modifications can be made without departing from the spirit of the invention. For example, the outriggers may be configured in patterns other than the generally X-shaped pattern shown in the drawings; various mast designs may be used (including cantilevered masts) , and other safety cage designs may be utilized.

Claims

1. A portable personnel lift comprising: a chassis, a mast carried by said chassis, a work platform elevatable by said mast, first and second outriggers removably connected to said chassis, first and second drive wheels carried by said first and second outriggers, first and second drive motors carried by said first and second outriggers, respectively, said first and second drive motors driving said first and second drive wheels, respectively, third and fourth outriggers removably connected to said chassis, third and fourth wheels carried by said third and fourth outriggers, respectively, and means for controlling said first and second drive motors .

2. The apparatus of claim 1 wherein said third and fourth wheels are casters and wherein said control means for said first and second drive motors steers the apparatus by rotating said first and second drive motors at different speeds or in different directions. 10

3. The apparatus of claim 2 further comprising spring brakes carried by said first and second drive wheels and wherein the apparatus may be pivoted around said first drive wheel by applying the brake to said first drive wheel and by energizing said second drive motor to cause said second drive wheel to rotate.

4. The apparatus of claim 1 further comprising a screw jack carried by each of said outriggers.

5. The apparatus of claim 1 wherein said four outrig- gers form a generally X-shaped pattern.

6. In a portable personnel lift having a chassis and an elevatable work platform, the improvement comprising: first and second outriggers removably connected to said chassis, first and second drive wheels carried by said first and second outriggers, first and second drive motors carried by said first and second outriggers, respectively, said first and second drive motors driving said first and second drive wheels, respectively, third and fourth outriggers removably connected to said chassis, third and fourth wheels carried by said third and fourth outriggers, respectively, and means for controlling said first and second drive motors . 11

7. The apparatus of claim 6 wherein said third and fourth wheels are casters and wherein said control means for said first and second drive motors steers the apparatus by rotating said first and second drive motors at different speeds or in different directions.

8. A portable personnel lift capable of being transported by a single person, moved through a standard thirty inch wide doorway, and readily converted by a single person to a self-propelled, steerable lift capable of achieving working platform heights of twenty-five to fifty feet, comprising: a chassis, a telescopic mast carried by said chassis, a work platform carried by and elevatable by said mast, a plurality of transport wheels carried by said chassis, said chassis and said telescopic mast being sized to pass through a standard thirty inch wide doorway on said transport wheels, first, second, third and fourth removable outriggers connectable to said chassis, each having inner and outer ends, 12

driving and steering assembly means including first and second drive motors and wheels carried at the outer ends of said first and second removable outriggers, respectively, providing sufficient stability that the lift may be driven while elevated, support wheels carried by the outer ends of said third and fourth removable outriggers, said first, second, third and fourth removable outriggers carrying the weight of said personnel lift when attached, and providing sufficient stability to achieve working platform heights of twenty-five to fifty feet, and driving and steering control means for causing said first and second drive motors to rotate to propel said lift and to cause said first and second drive motors to rotate either at different speeds or in different directions to steer said lift.

9. The apparatus of claim 8 wherein said wheels carried by said first and second outriggers are fixed and said wheels carried by said third and fourth outriggers are casters.

10. The apparatus of claim 8 wherein said inner ends of said first, second, third and fourth outriggers are connected to generally C-shaped members carried by said chassis.

11. The apparatus of claim 8 further comprising spring brakes carried by said first and second drive wheels.