Safety guard assembly for fork lift trucks

An overhead guard assembly for a pedestrian-operated industrial lift truck maneuvered by an arcuately shiftable handle and a vertically elongated mast supporting an article lifting implement. The overhead guard assembly has a fixed horizontally disposed structural member and a pivotable horizontally disposed structural member mounted adjacent the upper end of the mast. A vertically extending elongated shaft is connected to the pivotable structural member and is operatively connected to a handle by a drive linkage. The drive linkage rotates the elongated shaft as the handle is arcuately rotated whereby the pivotable structural member rotates in tandem with the handle to provide an overhead barrier above the handle and the operator's head.

TECHNICAL FIELD 
This invention relates to a safety device for an overhead guard assembly 
which could frequently prevent foreseeable injuries to operators of a 
pedestrian-operated industrial lift trucks. 
BACKGROUND ART 
Accidental injuries caused by operation of power-driven machinery and 
equipment are a serious problem in the workplace. Foreseeable personal 
injuries have occurred in the use of pedestrian-operated industrial lift 
trucks when objects fall from raised forks onto operators standing beside 
the truck. 
Pedestrian-operated industrial lift trucks are commonly used in warehouses 
and other storage facilities to move heavy objects from one area to 
another. These trucks have a pair of forks or other load handling 
apparatus mounted on a vertical lift which allows the operator to stack 
heavy loads at any height. This allows the operator to store loads in 
vertical tiers in hard to reach places. As cargo is raised above the 
operator's head by the fork lift, the operator becomes susceptible to 
injury. Foreseeably, the operator could sustain an injury if cargo that 
the lift truck mechanism dislodged, was elevating or transporting fell 
from the forks. This could result in a massive head injury and possibly 
even death for the operator. 
Pedestrian-operated lift trucks are moved and guided by an operator walking 
or riding alongside or behind the lift truck. The operator controls the 
lift truck's movements with an arcuately shiftable handle control. 
Overhead guard assemblies are provided on many lift trucks currently in 
use. One such guard assembly is cited in U.S. Pat. No. 3,844,382 to 
Mecklenburg which discloses a mast-mounted overhead guard for an electric 
lift truck. The overhead guard is pivotally attached to a vertically 
extending mast which positions it directly above the operator's station. 
The device pivots vertically as cargo is raised above the operator's head. 
The Mecklenburg guard assembly does not protect the operator standing to 
the side of the truck. 
Another type of guard assembly used for industrial lift trucks is disclosed 
in U.S. Pat. No. 3,934,679 to Lieptz which describes a retractable 
overhead guard for use on vertical lifting machines which protects an 
operator from falling material. The overhead guard assembly pivots 
vertically in response to the vertical positioning of the forks of the 
lift truck. The Lieptz device does not include any lateral protection to 
prevent objects being transported by the lift truck from falling on 
persons standing to the side of the overhead guard assembly. The operator 
of the pedestrian-operated industrial trucks typically walks or rides 
alongside or behind the truck which places him in harms way outside the 
guard coverage area. 
Loads transported moved, raised or lowered are often most vulnerable to 
tipping or dropping when the lift truck is turned or reversed. It is 
foreseeable that a heavy object being transported on the forks of the lift 
truck could fall on top of the operator, causing a crushing injury to the 
operator's head, shoulders, legs, feet or arms, potentially resulting in 
permanent injuries or even death. 
The above stated foreseeable hazards and others establish that there is a 
long-felt need for a device for preventing injury as a result of the 
operation of pedestrian-operated industrial lift trucks. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a simple and 
inexpensive overhead guard assembly for pedestrian-operated industrial 
lift trucks which will protect the operator standing beside or behind the 
lift truck from falling objects during the use of a pedestrian-operated 
lift truck. 
It is another object of the present invention to provide an overhead guard 
assembly having a simple mechanical linkage which will enable the guard 
assembly to turn in tandem with the handle control thereby providing the 
operator protection while manipulating the handle control. 
It is a further object of the invention to provide a motor and an 
electrical position encoder which will turn the overhead guard assembly in 
tandem with the handle control to provide an overhead barrier for 
protecting an operator while using the pedestrian-operated lift truck. 
Yet another object of the invention is to provide an overhead guard 
assembly which will provide a fan-shaped barrier for protecting an 
operator during the use of a pedestrian-operated lift truck. 
The above objects and other objects, features, and advantages of the 
present invention are readily apparent from the following detailed 
description of the best mode for carrying out the invention when taken in 
connection with the accompanying drawings.

BEST MODE OF THE INVENTION 
Referring to FIG. 1, a pedestrian-operated industrial lift truck 10 is 
shown which includes the overhead guard assembly 12. Overhead guard 
assembly 12 is made up of a fixed structural member 14 and a pivotable 
structural member 16. Fixed structural member 14 is attached to a mast 18 
which extends vertically from the lower platform 20 of the lift truck 10. 
An elongated shaft 22 attached to pivotable structural member 16 extends 
vertically with mast 18 to connect member 16 with drive linkage 24. 
The lift truck 10 has a lower platform 20 which-is supported by drive 
wheels 26 and rear wheels 28 in the illustrated embodiment. Other wheel 
arrangements commonly utilized in pedestrian-operated industrial lift 
trucks could incorporate the overhead guard assembly 12 of the present 
invention. 
Referring to FIGS. 1 and 2, rear wheels 28 are connected by a drive axle 30 
which is attached to a vertical shaft 32 extending to a handle 34. Handle 
34 extends rearwardly from the perimeter of lower platform 20. Handle 34 
has a hand grip control 36 on its distal end which controls the operation 
of the motor 38. 
A telescoping mast 40 extends vertically from lower platform 20 of lift 
truck 10. Telescoping mast 40 supports a pair of lifting forks 42, 44 
which carry the cargo load. It should be understood that a hook, magnet, 
shovel or other load engaging device could also be used instead of the 
forks 42, 44. Guard assembly 12 is positioned directly opposite lifting 
forks 42, 44 to provide protection for the operator. 
In an alternative embodiment of the invention, mast 18 could be eliminated 
from lift truck 10. The fixed structural member 14 could alternatively be 
attached to telescoping mast 40. Elongated shaft 22 would extend 
vertically with the mast 40 to connect pivotable structural member 16 to 
drive linkage 24. 
Referring now to FIG. 2, in one embodiment a mechanical drive linkage 24 is 
shown in greater detail. Axle 30 is connected to a shaft 32. Handle 34 is 
pivotally connected to shaft 32. Shaft 32 rotates about an axis "A" in 
response to handle 34 being turned clockwise or counterclockwise. The 
rotation of handle 34 is transferred through the shaft 32 which in turn 
rotates rear wheels 28. 
A gear 46 is mounted on and is rotated in tandem with the shaft 32. Another 
gear 48 is mounted on elongated shaft 22. A chain 50 is connected to both 
of the gears 46 and 48. Rotation of gear 46 about an axis "B" is 
transferred to gear 48 by chain 50. Gear 48 turns the elongated shaft 22 
which in turn rotates pivotable structural member 16. The pivotable 
structural member 16 rotates in tandem above the handle 34, providing a 
broader area of protection from falling objects in combination with the 
fixed structural member 14. 
FIG. 3 illustrates another embodiment of drive linkage 24' for the 
pedestrian-operated lift truck 10. An electrical position encoder 52 is 
mounted on shaft 32. The encoder 52 determines the relative rotational 
position of handle 34. The encoder 52 sends this position information via 
electrical wires 54 to a motor 56 mounted on elongated shaft 22. Motor 56 
rotates elongated shaft 22 in tandem with the rotation of handle 34. The 
elongated shaft 22 rotates the pivotable structural member 16 to provide a 
barrier of protection above the operator's head in combination with the 
fixed structural member 14. 
Referring now to FIG. 4, another embodiment of the overhead guard assembly 
12 is disclosed. Fixed structural member 14 supports pivotable structural 
members 58, 60. Pivotable structural members 58, 60 are attached to 
elongated shaft 22. As elongated shaft 22 is moved by movement of the 
handle 34, members 58, 60 rotate arcuately upon fixed structural member 14 
at their distal ends. Members 58, 60 move relative to fixed structural 
member 14, to provide an increased continuous area of protection above the 
operator's head. 
FIG. 5 illustrates another alternative embodiment of the drive linkage 24" 
wherein elongated shaft 22, which is connected to pivotable structural 
member 16, is shifted by a series of gears 62, 64, and 66. These gears 
translate the motion of shaft 32 to shaft 22 and member 16, thereby 
rotating the pivotable member 16 to a desired position. 
While several different embodiments of the present invention are described 
above, it will be readily appreciated by one of ordinary skill in the art 
that many other combinations and variations may be used to achieve the 
simple and effective safety guard of the present invention. The preceding 
description of different illustrated embodiments should not be read to 
limit the scope of the applicant's invention which should be construed in 
accordance with the broad scope of the following claims.