Implements or apparatus for applying pushing or pulling force – Apparatus for hauling or hoisting load – including driven... – Device includes rotatably driven – cable contacting drum
Reexamination Certificate
1999-11-18
2002-06-18
Marcelo, Emmanuel M. (Department: 3653)
Implements or apparatus for applying pushing or pulling force
Apparatus for hauling or hoisting load, including driven...
Device includes rotatably driven, cable contacting drum
C254S369000, C254S376000
Reexamination Certificate
active
06406001
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a chain lever hoist and, more particularly, to a chain lever hoist wherein a load sheave is rotated to wind up and down a load chain passing over the load sheave by the reciprocating operation of an operating lever.
2. Description of the Prior Art
Known as a chain lever hoist of this type is, for example, the one disclosed in Japanese Patent Publication No. 54(1979)-9381 and shown in FIG.
10
.
As shown in
FIG. 10
, in the chain lever hoist, a load sheave
4
over which a load chain
3
passes in engaging relation is supported in rotatable relation between spaced apart first and second side plates
1
and
2
via two bearings
5
,
6
. The load sheave
4
has a shaft bore in which a drive shaft
7
is inserted in rotatable relation, and a mechanical brake
8
is provided on the drive shaft
7
at the outside of the second side plate
2
.
The mechanical brake
8
comprises a second hub
11
connected to the drive shaft
7
in non-rotatable relation relative thereto and having a cylindrical portion
9
and a flange
10
, an anti-reverse gear
12
supported on the cylindrical portion
9
of the second hub
11
in freely rotatable relation, two lining plates
13
and
14
supported on the cylindrical portion
9
of the second hub
11
at opposite sides of the anti-reverse gear
12
, and an anti-reverse pawl
16
pivoted to a pawl shaft
15
projecting from the second side plate
2
and so biased as to be engaged with the anti-reverse gear
12
.
A first hub
17
having engaging teeth
21
around an outside thereof is threadedly mounted on the drive shaft
7
at the axial outside (at the right side as viewed in
FIG. 10
) of the mechanical brake
8
. An operating handle
18
is fitted onto the drive shaft
7
and is fixed to the first hub
17
with screws
19
,
20
so as to be non-rotatable relative thereto at the axial outside of the first hub
17
. Further, a coil spring
28
for biasing the first hub
17
and the second hub
11
to be forced away from each other is interposed between the first hub
17
and the second hub
11
.
A lock nut
30
is fixed to the drive shaft
7
by a set pin at an end of the drive shaft
7
on the side thereof on which the operating handle
18
is fitted, with a predetermined spaced interval from the operating handle
18
, so as to be axially immovable, and thereby the range of axial movement of the first hub
17
movable together with the operating handle
18
is limited. On the other hand, a reduction gear mechanism
24
is provided at the other axial end of the drive shaft
7
, to transmit the drive applied from the drive shaft
7
to the load sheave
4
at a predetermined reduction ratio.
A gear cover
25
for covering the reduction gear mechanism
24
is fixed to the first side plate
1
, and a brake cover
26
for covering the mechanical brake
8
, formed having an opening
29
for the first hub
17
to be fitted in, is fixed to the second side plate
2
. An operating lever
22
is loosely fitted around the outside of the first hub
17
at the axial outside of the brake cover
26
. The operating lever
22
is provided with an engaging pawl
23
which can be selectively switched to a normal position at which only a normal rotation drive of the operating lever
22
is transmitted, a reverse position at which only a reverse rotation drive of the operating lever is transmitted, and a neutral position at which the engaging pawl
23
and the engaging teeth
21
are not engaged with each other, to disengageably engage with engaging teeth
21
of the first hub
17
.
When a load is hoisted up by use of the chain lever hoist thus constructed, the engaging pawl
23
of the operating lever
22
is first switched to the normal position by the operation of a selector lever
27
to be brought into engagement with the engaging teeth
21
of the first hub
17
and, then, the operating lever
22
is reciprocated to screw the first hub
17
forward so as to press the mechanical brake
8
, whereby the load sheave
4
is allowed to rotate in the normal rotation direction through the drive shaft
7
and the reduction gear mechanism
24
. On the other hand, when the load is lowered down, the engaging pawl
23
of the operating lever
22
is first switched to the reverse position by the operation of the selector lever
27
to be brought into engagement with the engaging teeth
21
of the first hub
17
and, then, the operating lever
22
is reciprocated to screw the first hub
17
backward, so as to release the mechanical brake
8
, whereby the load sheave
4
is allowed to rotate in the reverse rotation direction under the weight of the load to permit the lowering of the load. Along with the lowering of the load, the drive shaft
7
is reversed, so that the first hub
17
is screwed forward again to put the mechanical brake
8
into action. By repetition of this action and release of the mechanical brake
8
, the load can be gradually lowered down.
Further, when the load chain
3
is desired to be adjusted in length at the start of working, for example, the engaging pawl
23
of the operating lever
22
is switched to the neutral position by the operation of the selector lever
27
, not to be brought into engagement with the engaging teeth
21
. Then, the pressing of the first hub
17
against the mechanical brake
8
is released by a spring force of the coil spring
28
and, as a result of this, the first hub
17
comes to be rotatable together with the drive shaft
7
to thereby produce the free rotation condition. If a load is suspended from the load chain
3
on the loaded side, a large thrust from the weight of the load is applied to the drive shaft
7
, so that even if the engaging pawl
23
is switched to the neutral position, since the first hub
17
presses the mechanical brake
8
against the spring force of the coil spring
28
, the free rotation state will not be produced.
However, when the free rotation operation of the chain lever hoist thus constructed is carried out, since the first hub
17
and the operating handle
18
are in contact with the operating lever
22
, the contact resistance can hinder smooth rotation of the first hub
17
to cause the first hub
17
to rotate relative to the drive shaft
7
and, as a result of this, there may be produced a possible problem that the first hub
17
may press the mechanical brake
8
to put the mechanical brake
8
into action.
On the other hand, it may be practical to allow for the contact resistance between the first hub
17
and the operating handle
18
and the operating lever
22
and use the coil spring
28
having a spring force sufficient for the first hub
17
to rotate against the contact resistance. However, it is hard to pre-select the coil spring
28
having the right spring force corresponding to the contact resistance. Besides, since the contact resistance varies depending on the degree of abrasion or wear of the contacting parts, the rotation of the first hub
17
varies depending on the degree of the abrasion or wear. Further, the chain lever hoist is used in various conditions, such as the condition in which the chain lever hoist is suspended from overhead and the operating lever is in vertical orientation, the condition in which the chain lever hoist is suspended from overhead and the operating lever is in somewhat tilt with respect to the vertical direction, or the condition in which the chain lever hoist is not suspended from overhead and is put in horizontal orientation. Depending on the use condition of the chain lever hoist, variation is caused in the application of the weight of the first hub
17
, the operating handle
18
and the operating lever
22
, which in turn causes variation in the contact resistance in each use condition. Because of this, the ability for the first hub
17
to be rotated relative to the drive shaft
7
, in other words, the ability for the mechanical brake
8
to be engaged in the free rotation state, is varied and, therefore, there is the disadvantage that a stable fre
Elephant Chain Block Co., Ltd.
Kilpatrick & Stockton LLP
Marcelo Emmanuel M.
Marcou George T.
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