Elevator – industrial lift truck – or stationary lift for vehicle – Industrial lift truck or required component thereof
Reexamination Certificate
1998-12-01
2001-07-24
Ellis, Christopher P. (Department: 3652)
Elevator, industrial lift truck, or stationary lift for vehicle
Industrial lift truck or required component thereof
C187S238000
Reexamination Certificate
active
06264004
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a mast apparatus for lift trucks and a lift truck equipped with a mast apparatus. More specifically, the invention relates to a mast apparatus and a lift truck, in which a carrier for carrying a load-handling attachment is lifted and lowered by a lift chain along a guide mast, and the lift chain tends to swing.
FIGS. 1 and 2
show typical states of a conventional mast apparatus in the form of a mast-guided fork lift, with a fork lowered to and slightly lifted from a floor or ground. The mast apparatus has a pair of left and right outer rails
1
, in a view along a longitudinal direction of a vehicle body (not shown) of a fork lift truck equipped with the mast apparatus. The left and right outer rails
1
are interconnected for integration by a plurality of beam members extending in a transverse direction of the vehicle body. A lowest beam member
3
L has support brackets
5
integrally provided thereto for a pivotal support on a front axle (not shown) as part of a body of the fork lift truck to permit a pivotal motion in the longitudinal direction. An upper beam member
3
U is provided with L-shaped brackets
4
at left and right ends thereof, and is integrally connected via the brackets
4
to the left and right outer rails
1
. For the outer rails
1
to be longitudinally tilted relative to the vehicle body, left and right tilt cylinders
9
are interposed therebetween. Each tilt cylinder
9
is pivoted at a base end thereof on a part
7
of the vehicle body, and at an end of a piston rod
9
P thereof to one of the outer rails
1
.
The left and right outer rails
1
have a pair of left and right inner rails
11
provided on transversely inner sides thereof in a vertically movable manner. The left and right inner rails
11
are interconnected for integration by a plurality of beam members extending in the transverse direction. An uppermost beam member
13
U projects at left and right ends thereof outside the left and right outer rails
1
. The left and right ends of the uppermost beam member
13
U each have a chain wheel bracket
15
integrally provided thereto.
A chain wheel
17
is provided on a transversely inner side of the chain wheel bracket
15
, and is rotatably supported thereon. A lift chain
19
is applied over the chain wheel
17
, and is connected at one end thereof to an anchor bolt
23
, which is provided to a lower part of a carriage
21
that is vertically movable along the inner rails
11
that serve as guide masts therefor. The other end of the lift chain
19
is connected to another anchor bolt
25
, which is attached near an upper part of outer rail
1
in a vertically shiftable manner. The carriage
21
carries a plurality of forks
27
for handling a load.
The inner rails
11
are actuated to vertically move relative to the outer rails
1
, so that the carriage
21
and the forks
27
are lifted and lowered along the inner rails
11
. For the actuation, the outer rails
1
are equipped with a pair of left and right lift cylinders
29
, which have their vertically movable piston rods
29
P connected to the uppermost beam member
13
U between the inner rails
11
.
As the piston rods
29
P of the lift cylinders
29
vertically move, the inner rails
11
vertically move relative to the outer rails
1
, causing the carriage
21
and the forks
27
to be lifted and lowered. When the fork lift truck travels, the forks
27
are held in a slightly lifted position as in FIG.
2
.
As the fork lift truck travels, a length of the lift chain
19
between the chain wheel
17
and the anchor bolt
23
has a varying tendency to swing in the longitudinal and transverse directions, as in
FIG. 2
, depending such as on the condition of travel route as well as on a loading condition to the forks
27
. The lift chain
19
may have a large swing, directly hitting the outer rail or the like, causing a coat on the chain such as grease to be spattered, producing uncomfortable sounds, and/or interrupting a sight of a lift operator. Frequent direct hits on the outer rail may render a potential chain life shorter.
SUMMARY OF THE INVENTION
The present invention has been achieved with such points in view.
It therefore is an object of the present invention to provide a mast apparatus for lift trucks, in which a lift chain has a reduced tendency to swing, to cope with conventional issues. It also is an object of the present invention to provide a lift truck equipped with a mast apparatus, in which a lift chain has a reduced tendency to swing, to cope with conventional issues.
To achieve the object, an aspect of the invention provides a mast apparatus for lift trucks, comprising a carrier for carrying a load-handling attachment, a lift drive for lifting the carrier, the lift drive including a lift chain connected to the carrier, a guide mast for guiding the carrier along the guide mast, and a swing restrictor provided on the guide mast for restricting a swing motion of the lift chain.
Another aspect of the invention provides a lift truck comprising a vehicle body supported by a plurality of wheels, a carrier for carrying a load-handling attachment, a lift drive for lifting the carrier, the lift drive including a lift chain connected to the carrier, a guide mast supported by the vehicle body for guiding the carrier along the guide mast, and a swing restrictor provided on the guide mast for restricting a swing motion of the lift chain.
According to the aspects of the invention, a lift chain has a tendency to swing and may make a large swing motion against a guide mast. However, the guide mast has a swing restrictor provided thereon, which restricts the swing motion of the lift chain so that the lift chain has a reduced tendency to swing.
REFERENCES:
patent: 3061047 (1962-10-01), Gunning
patent: 3360078 (1967-12-01), Hopfeld
patent: 3854699 (1974-12-01), Garnett
patent: 3972388 (1976-08-01), McVeen
patent: 5752583 (1998-05-01), Schönewald
patent: 2-86600 (1990-03-01), None
patent: 7-157295 (1995-06-01), None
patent: 7-187592 (1995-07-01), None
Ellis Christopher P.
McDermott & Will & Emery
Nissan Motor Co,. Ltd.
Tran Thuy V.
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