Information
-
Patent Grant
-
6406001
-
Patent Number
6,406,001
-
Date Filed
Thursday, November 18, 199924 years ago
-
Date Issued
Tuesday, June 18, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Marcou; George T.
- Kilpatrick Stockton LLP
-
CPC
-
US Classifications
Field of Search
US
- 254 342
- 254 352
- 254 369
- 254 376
-
International Classifications
-
Abstract
For providing a chain lever hoist that can ensure a stable free rotation operation over a long term with a simple design, improvement is made in the chain lever hoist wherein an engaging pawl is switched to a neutral position, at which the engaging pawl is not allowed to engage with engaging teeth in the forward direction or a reverse direction, by the operation of a selector lever and then a load chain on the non-loaded side is pulled or an operating handle is rotated in the reverse direction to thereby produce the free rotation state just the way it is, the improvement being such that the operating lever is rotatably supported on a brake cover at its opening with a predetermined spaced interval from a first hub. By virtue of this, the first hub is allowed to rotate together with the drive shaft, without contacting with the operating lever, during the free rotation operation, and as such can attain reliable free rotation operation.
Description
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 free-rotation operation cannot be attained.
SUMMARY OF THE INVENTION
It is the object of the present invention is to provide a chain lever hoist that can attain a stable free-rotation operation for a long term with simple design.
The present invention provides a chain lever hoist comprising a load sheave with which a load chain is engaged; a first hub forming engaging teeth around an outside thereof; an operating lever having an engaging pawl detachably engageable with the engaging teeth and loosely fitted around the outside of the first hub; a mechanical brake comprising a second hub interposed between the first hub and the load sheave, an anti-reverse gear supported on the second hub, two brake disks supported on the second hub at the opposite sides of the anti-reverse gear, and an anti-reverse pawl disposed at the outside of the anti-reverse gear and engageable with the anti-reverse gear; a drive shaft, on which the first hub is threadedly mounted and with which the second hub is connected in non-rotatable relation relative thereto and onto which the load sheave is fitted, for allowing drive applied from the operating lever to be transmitted to the load sheave through a reduction gear mechanism; a biasing means, interposed between the first hub and the second hub, for biasing the first hub and the second hub to be away from each other, the biasing means having a biasing force of such an extent that can keep the mechanical brake in its released state during free rotation operation and also put the mechanical brake into action in the free rotation operation when a rotation drive exceeding contact resistance between the drive shaft and the first hub is applied to the drive shaft; and a brake cover for covering the mechanical brake, the brake over being formed having an opening for the first hub to be inserted in, wherein when engagement between the engaging pawl and the engaging teeth is released in the state in which no load is applied to the load chain on a loaded side thereof, pressing of the first hub against the mechanical brake can be released by the biasing force of the biasing means to put the first hub and the drive shaft into a rotatable-together state to thereby produce free rotation condition and wherein the operating lever is rotatably supported on the brake cover at the opening thereof with a predetermined spaced interval from the first hub.
In this arrangement, the operating lever is rotatably supported on the brake cover at the opening thereof with a predetermined spaced interval from the first hub. Thus, the first hub is rotated together with the drive shaft without contacting with the operating lever, thus ensuring smooth and reliable rotation of the first hub. By virtue of this, the condition for the relative rotation of the first hub to the drive shaft to be caused, in other words, the condition for the mechanical brake to be put in action in the free rotation state, can be determined by only the biasing force of the biasing means. Thus, it is good enough for attainment of the reliable free rotation operation to adopt the biasing means having a biasing force of such an extent that can put the mechanical brake into action when the rotation drive exceeding the contact resistance between the drive shaft and the first hub is applied to the drive shaft in the free rotation state. Thus, the stable free rotation operation can be ensured for a long term with the simple design.
According to the present invention, it is preferable that the chain lever hoist further comprises an operating member fitted onto the drive shaft and mounted on the first hub in non-rotatable relation relative thereto and that a cylindrical insertion portion for inserting therein the operating member is formed in the operating lever, with a predetermined spaced interval from the operating member.
In this arrangement, the pressing of the first hub against the mechanical brake can be released simply by rotating the operating member in the reverse direction for the free rotation operation, and as such can facilitate the free rotation operation. Also, since the operating member is mounted on the first hub with a predetermined spaced interval from the cylindrical insertion portion of the operating lever, the operating member can be prevented from contacting with the operating lever during the free rotation operation, and as such can ensure the smooth and reliable rotation.
According to the present invention, it is preferable that the brake cover has a brake-cover-side connecting portion for connecting the brake cover with the operating lever, while on the other hand, the operating lever has a lever-side connecting portion for connecting the operating lever with the brake cover, that the brake-cover-side connecting portion and the lever-side connecting portion are connected together by connecting means, and that the connecting means is arranged with a predetermined spaced interval from the first hub.
In this arrangement, since the operating lever and the brake cover are connected with each other by the connecting means arranged with a predetermined spaced interval from the first hub, the axial movement of the operating lever and the brake cover are limited, while also improved strength of the connecting portion thereof can be attained. By virtue of this, the operating lever can be kept from contacting the first hub and the operating member due to a tilted orientation of the operating lever resulting from the reciprocating motion of the operating lever, for example. Thus, a further stable free rotation operation can be attained.
According to the present invention, it is preferable that the connecting means comprises a holding member for holding the brake-cover-side connecting portion and the lever-side connecting portion in sandwich relation and a retaining member which is held in sandwich relation together with the brake-cover-side connecting portion and the lever-side connecting portion.
In this arrangement, the retaining member is fitted in the holding member and also the lever-side connecting portion and the brake-cover-side connecting portion are fitted by the retaining member, whereby the operating lever can be rotatably supported on the brake cover.
By virtue of this, for example the mount of the operating lever on the brake cover can readily and surely be attained by the use of the holding member arranged in advance, without taking such a step that after the brake-cover-side connecting portion and the lever-side connecting portion are held in sandwich relation by the holding member, the holding member is crimped.
According to the present invention, it is preferable that the drive shaft has a screw-thread portion, for the first hub and the second hub to be both threadedly mounted on, which is formed being substantially equal in diameter, and a fitting groove formed in the screw-thread portion at a certain point thereof, whereby the first hub and the second hub are threadedly mounted on the screw-thread portion and also a limiting means is fitted in the fitting groove so that an axial movement of the second hub can be limited.
In this arrangement, since the screw-thread portion on which the first hub and the second hub are both threadedly mounted is formed being substantially equal in diameter, rigidity of the drive shaft can be increased and thus durability of the chain lever hoist can be increased. For example in a case where the drive shaft is splined at a portion thereof for mounting the second hub thereon and is threaded at a portion thereof for mounting the first hub thereon, the drive shaft will inevitably be reduced in rigidity and durability. This is because since the second hub must be mounted first prior to the mounting of the first hub in the assembling work, the threaded portion of the drive shaft cannot help being made smaller in diameter than the splined portion and also a portion of the drive shaft extending between the splined portion and the threaded portion cannot help being made smaller in diameter than those portions for the machining need. The arrangement of the invention in which the first hub and the second hub are threadedly mounted on the screw-thread portion of substantially equal in diameter and also the limiting means is fitted in the fitting groove, whereby the first hub can be screwed forward and backward along the drive shaft and also the second hub can be non-rotatable relative to the drive shaft can provide increased rigidity of the drive shaft and thus improved durability of the chain lever hoist.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will now be described with reference to the accompanying drawings wherein:
FIG. 1
is a longitudinal sectional view showing a chain lever hoist as one embodied form of the present invention;
FIG. 2
is a front view of a principal part of the chain lever hoist shown in
FIG. 1
;
FIG. 3
is a side view showing the drive shaft of the chain lever hoist shown in
FIG. 1
;
FIG. 4
is a side view showing a coil spring of the chain lever hoist shown in
FIG. 1
;
FIG. 5
is a side view in section showing a first cover of the operating lever of the chain lever hoist shown in
FIG. 1
;
FIG. 6
is a side view in section showing a second cover of the operating lever of the chain lever hoist shown in
FIG. 1
;
FIG. 7
is a side view in section showing a brake cover of the chain lever hoist shown in
FIG. 1
;
FIG. 8
is a side view in section showing a holding member of the chain lever hoist shown in
FIG. 1
;
FIG. 9
is a side view in section showing a retaining member of the chain lever hoist shown in
FIG. 1
; and
FIG. 10
is a side view in section showing a conventional type of chain lever hoist.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the accompanying drawing figures, an example of the preferred embodiment of the invention is described below.
Referring to
FIG. 1
, there is shown a longitudinal sectional view showing a chain lever hoist as one embodied form of the present invention. In the chain lever hoist, a load sheave
34
over which a load chain
33
passes in engaging relation is supported in rotatable relation between spaced apart first and second side plates
31
and
32
via two bearings
35
,
36
. The first side plate
31
and the second side plate
32
are fixed together with a gear cover
75
and a brake cover
77
, as mentioned later, through a pair of upper stay bolts
78
and a pair of lower stay bolts
79
(only one of each pair of stay bolts are presented in FIG.
1
).
The load sheave
34
has a shaft bore in which a drive shaft
37
is inserted in rotatable relation. As shown in
FIG. 3
as well, the drive shaft
37
has a first gear
48
formed at one axial end portion of the drive shaft, a load sheave fitting portion
49
for fitting the load sheave
34
to it, a screw-thread portion
50
of substantially equal in diameter, a fitting groove
51
formed in the screw-thread portion
50
at a certain point thereof, an operating handle fitting portion
52
, formed smaller in diameter than the screw-thread portion
50
, for fitting an operating handle
59
thereto, and a lock nut screwing portion
53
, formed at the other end portion of the drive shaft, for threadedly mounting thereon a lock nut mentioned later.
A mechanical brake
38
is provided at the axially outside of the load sheave
34
(at the left side of
FIG. 1
) and at the outside of the first side plate
31
. The mechanical brake
38
is provided with a second hub
39
connected to the drive shaft
37
in non-rotatable relation relative thereto. The second hub
39
is threadedly mounted on the screw-thread portion
50
of the drive shaft
37
and its axial movement is limited by a stop member
54
of a limiting means being fitted in the fitting groove
51
. The second hub is formed in one piece having a flange
43
and a cylindrical portion
44
extending axially outwardly from the flange
43
. The first lining plate
40
forming a brake disk, an anti-reverse gear
41
and a second lining plate
42
forming a brake disk are supported on the cylindrical portion
44
of the second hub
39
in freely rotatable relation in the order presented from the axial outside.
Two pawl shafts
45
are provided on the first side plate
31
at opposed positions. Anti-reverse pawls
46
engageable with the anti-reverse gear
41
are pivoted on the two pawl shafts
45
in swingable relation, respectively. Further, pawl springs
47
for biasing the anti-reverse pawls
46
toward the anti-reverse gears
41
are provided on the two pawl shafts
45
between the anti-reverse pawls
46
and the first side plate
31
, respectively. The mechanical brake
38
is composed of the second hub
39
, the anti-reverse gear
41
, the first lining plate
40
, the second lining plate
42
and the anti-reverse pawl
46
.
A first hub
55
is screwably mounted on the screw-thread portion
50
of the drive shaft
37
at the axial outside of the mechanical brake
38
. The first hub
55
is of cylindrical configuration and has engaging teeth
56
formed around the outside thereof, a spring receiving portion
58
formed in recessed configuration at an end thereof on the axially inward side (at the right side of
FIG. 1
) and a pressing portion
57
, formed around the outside of the spring receiving portion, for pressing the first lining plate
40
of the mechanical brake
38
.
A coil spring
92
forming a biasing means is interposed between the spring receiving portion
58
of the first hub
55
and the second hub
39
. The coil spring
92
is composed of a compression spring, as shown in
FIG. 4
, biasing the first hub
55
and the second hub
39
to be forced away from each other, so that the release of the mechanical brake
38
can be held during the free-rotation operation. The coil spring
92
used has a spring force of such an extent that can put the mechanical brake
38
into action or can allow the first hub
55
to be screwed forward when a rotational drive in excess of the contact resistance between the drive shaft and the first hub
55
is applied to the drive shaft
37
in the free rotation state.
Further, an operating handle
59
forming an operating member is fitted onto the operating handle fitting portion
52
of the drive shaft
37
at the axial outside of the first hub
55
. The operating handle
59
is composed of a base
60
and a cylindrical grip
61
continuously projecting from around the outside of the base
60
. The base
60
is fixed to the first hub
55
by two screws
62
,
63
in non-rotatable relation relative to the first hub.
A lock nut
64
is threadedly mounted on the drive shaft
37
at an end thereof at the axial outside of the operating handle
59
, with a predetermined spaced interval from the operating handle
59
fitted onto the drive shaft
37
. The lock nut
64
is fixed to the drive shaft
37
at the end portion thereof by a set pin
65
, so as to be axially immovable, and thereby the range of axial movement of the first hub
55
moving together with the operating handle
59
is limited.
On the other hand, the drive shaft
37
is supported at the other axial end thereof by a bearing
66
, and a reduction gear mechanism
67
having a plurality of reduction gears, which forms the gear transmission mechanism, is provided between the bearing
66
and the load sheave
34
at the outside of the second side plate
32
. The reduction gear mechanism
67
is composed of a first gear
48
formed on the drive shaft
37
at an end thereof, second gears
70
and
71
engaged with the first gear
48
and formed on a pair of intermediate shafts
68
and
69
, respectively, third gears
72
and
73
formed on the pair of intermediate shafts
68
and
69
, respectively, as in the second gears, and a fourth gear
74
connected with an extended part of the load sheave
34
and engaged with the third gears
72
and
73
. The drive applied from the drive shaft
37
is transmitted from the first gear
48
to the second gears
70
,
71
engaged with the first gear and in turn is transmitted from the intermediate shafts
68
,
69
supporting thereon the second gears
70
,
71
to the fourth gear
74
through the third gears
72
,
73
supported on the intermediate shafts
68
,
69
. Thus, the drive applied from the drive shaft
37
is transmitted to the load sheave
34
at a predetermined reduction ratio.
A gear cover
75
for covering the reduction gear mechanism
67
is mounted on the second side plate
32
. The pair of intermediate shafts
68
,
69
are rotatably supported between the second side plate
32
and the gear cover
75
at side ends thereof via bearings.
On the other hand, a brake cover
77
for covering the mechanical brake
38
, which forms therein an opening
76
for the first hub
55
to be inserted in, is mounted on the first side plate
31
, as shown in FIG.
7
. The first hub
55
is threadedly mounted on the screw-thread portion
50
of the drive shaft
37
in such a state as to be inserted from the opening
76
of the brake cover
77
into the axially inside thereof.
In the illustrated embodiment, an operating lever
81
is loosely fitted around the outside of the first hub
55
and is rotatably supported at the opening
76
of the brake cover
77
, with a predetermined spaced interval from the first hub
55
.
The operating lever
81
is formed by opposed first and second covers
82
,
83
being put together with a plurality of bolts (only two bolts
84
,
85
are presented in FIG.
1
). An engaging pawl
80
detachably engageable with the engaging teeth
56
of the first hub
55
is swingably fitted in between the first cover
82
and the second cover
83
by a pivot
102
having a selector lever
86
at the head. A presser
87
for pressing the engaging pawl
80
toward the engaging teeth
56
, a receiving member
88
receiving therein the presser
87
, and a spring
89
, interposed between the presser
87
and the receiving member
88
, for biasing the presser
87
toward the engaging pawl
80
, are provided between the first cover
82
and the second cover
83
.
As shown in
FIG. 2
, the engaging pawl
80
is provided with a forward engaging projection
90
which is engaged with the engaging teeth
56
to transmit the drive from the operating lever
81
to the first hub
55
only when the first hub
55
is rotated in the normal rotation direction (or is rotated in the hoisting direction) and a backward engaging projection
91
which is engaged with the engaging teeth
56
to transmit the drive from the operating lever
81
to the first hub
55
only when the first hub
55
is rotated in the reverse rotation direction (or is rotated in the lowering direction). The engaging pawl
80
is selectively switched to one of a normal position at which the forward engaging projection
90
is engaged with the engaging teeth
56
of the first hub
55
to permit the transmission of only the normal rotation drive of the operating lever
81
, a reverse position at which the backward engaging projection
91
is engaged with the engaging teeth to permit the transmission of only the reverse rotation drive, and a neutral position at which the engaging pawl
80
is not engaged with the engaging teeth
56
.
In the second cover
83
is formed an aperture for loosely fitting the first hub
55
in it, as shown in
FIG. 6. A
marginal portion around the aperture of the second cover
83
forms a lever-side connecting portion
93
for connecting the operating lever with the brake cover
77
. On the other hand, a marginal portion around the opening
76
of the brake cover
77
forms a brake-cover-side connecting portion
94
for connecting the brake cover with the operating lever
81
. The lever-side connecting portion
93
and the brake-cover-side connecting portion
94
are connected with each other by connecting means
95
spaced apart from the first hub
55
with a predetermined interval.
In more detail, the connecting means
95
includes a cylindrical holding member
99
having flanges
96
,
97
at opposite ends thereof and a recessed portion
98
formed at a location adjoining the flange
96
, as shown in
FIG. 8
, and a ring-shaped retaining member
100
held in sandwich relation, together with the lever-side connecting portion
93
and the brake-cover-side connecting portion
94
, as shown in FIG.
9
. The retaining member
100
is fitted in the recessed portion
98
of the holding member
99
, and the lever-side connecting portion
93
and the brake-cover-side connecting portion
94
are fitted in between both flanges
96
,
97
in overlapping relation with each other, whereby the axial movement of the operating lever
81
and the brake cover
77
are limited and also the operating lever
81
is rotatably supported on the brake cover
77
, while the strength of the connecting portion is intended to be increased. This can prevent the tilt of the operating lever
81
resulting from the reciprocating motion of the operating lever
81
, and as such can allow the operating lever
81
to be well kept from contacting with the first hub
55
and the operating handle
59
. Thus, the stable free rotation operation can be attained over a long term. Also, the use of the retaining member
100
in combination with the holding member
99
as the connecting means
95
can yield simple and reliable mount of the operating lever
81
on the brake cover
77
by the use of the holding member
99
arranged in advance, without taking such a step that after the brake-cover-side connecting portion
94
and the lever-side connecting portion
93
are held in sandwich relation by the holding member
99
, the holding member
99
is crimped.
A cylindrical insertion portion
101
, projecting axially outwardly, for inserting the operating handle
59
therein is formed in the first cover
82
, spaced apart from the outer periphery of the base
60
of the operating handle
59
with a predetermined interval, as shown in FIG.
5
.
Now, the usage of the chain lever hoist thus constructed of the illustrated embodiment will be described.
First, a description will be given on the hoist of or the lowering of a load suspended from a lower hook (not shown) provided at the end of the load chain
33
on the loaded side thereof (on which load is applied). When a load is hoisted up, the engaging pawl
80
is positioned at the normal position by the operation of the selector lever
86
, first, and then the operating lever
81
is operated in reciprocation. Then, the first hub
55
is screwed forward along the drive shaft
37
by the drive from the operating lever
81
to press the first lining plate
40
of the mechanical brake
38
. Thereby the drive shaft
37
is driven in the normal rotation direction through the second hub
39
coupled with the drive shaft
37
in such a manner as to be non-rotatable relative thereto. When the drive shaft
37
is driven, the drive is transmitted to the load sheave
34
through the reduction gear mechanism
67
and thereby the load sheave
34
is rotated in the direction for the load to be hoisted up. As a result of this, the load suspended from the lower hook provided at the end of the load chain
33
running over the load sheave
34
is hoisted up. The suspended load is kept in its hoisted position by the operation of the mechanical brake
38
or by the engagement of the anti-reverse pawl
46
with the anti-reverse gear
41
.
When the load is lowered down, the engaging pawl
80
is positioned at the reverse position by the operation of the selector lever
86
, first, and then the operating lever
81
is operated in reciprocation. Then, the first hub
55
is screwed backward along the drive shaft
37
by the drive from the operating lever
81
to release the pressing of the first hub
55
against the mechanical brake
38
, so that the mechanical brake
38
is released. As a result of this, the drive shaft
37
is put into a freely rotatable state and thus is rotated in the reverse rotation direction under the weight of load, so that the load is lowered down. On the other hand, the reverse rotation of the drive shaft
37
causes the first hub
55
threadedly engaged with the drive shaft
37
to be screwed forward again along the drive shaft
37
, to press the first lining plate
40
. As a result of this, the mechanical brake
38
acts again to prevent the rotation of the drive shaft
37
in the reverse rotation direction. Thus, when the load is lowered down, the mechanical brake
38
is made active and inactive alternately so that the load sheave
34
can be allowed to rotate in the lowering direction little by little. The suspended load is lowered down in this manner.
Further, when the load chain
33
is desired to be adjusted in length at the start of working, for example, the engaging pawl
80
is switched to the neutral position by the operation of the selector lever
86
and then the load chain
33
on the non-loaded side thereof is pulled or the operating handle
59
is rotated in the reverse direction, to thereby produce the free rotation state just the way it is. In other words, in the state in which no load is applied to the load chain
33
and also the engagement between the engaging pawl
80
and the engaging teeth
56
is released, the pressing of the first hub
55
against the first lining plate
40
of the mechanical brake
38
is released by the spring force of the coil spring
92
. As a result of this, the first hub
55
and the drive shaft
37
come into a state where they rotate together and thereby the free rotation occurs. If a load is applied to the load chain
33
on the loaded side thereof or a load is suspended from the lower hook, a large thrust from the weight of the load is applied to the drive shaft
37
, so that even if the engaging pawl
80
is switched to the neutral position, the first hub
55
will press the first lining plate
40
of the mechanical brake
38
against the spring force of the coil spring
92
, so the free rotation state will not be produced. Further, when the load chain
33
on the load side thereof is pulled in the free rotation state so suddenly that the rotation drive exceeding the contact resistance between the drive shaft and the first hub
55
is applied to the drive shaft
37
, the mechanical brake
38
is put into action against the spring force of the coil spring
92
. Thus, in this case also, the free rotation is released to ensure the safety.
According to the chain lever hoist of the illustrated embodiment, since the operating lever
81
is supported with a predetermined spaced interval from the first hub
55
, the first hub
55
can be rotated together with the drive shaft
37
without contacting with the operating lever
81
, thus ensuring smooth and reliable rotation of the first hub
55
. By virtue of this, the condition for the relative rotation of the first hub
55
to the drive shaft
37
to be caused, in other words, the condition for the mechanical brake
38
to be put in action in the free rotation state, can be determined by only the spring force of the coil spring
92
. Thus, it is good enough for attainment of the reliable free rotation operation to adopt the coil spring
92
having spring force to such an extent that can put the mechanical brake
38
into action when the rotation drive exceeding the contact resistance between the drive shaft and the first hub
55
is applied to the drive shaft
37
in the free rotation state. Thus, the stable free rotation operation can be ensured for a long term with the simple design.
According to the chain lever hoist of the illustrated embodiment, since the operating handle
59
is mounted on the first hub
55
in such a manner as to be non-rotatable relative thereto, the pressing of the first hub
55
against the mechanical brake
38
can be released simply by rotating the operating handle
59
in the reverse direction for the free rotation operation, thus attaining facilitated free rotation operation. Besides, since the operating handle
59
is mounted on the first hub
55
with a predetermined spaced interval from the cylindrical insertion portion
101
of the operating lever
81
, the operating handle
59
can be prevented from contacting with the operating lever
81
during the free rotation operation, to ensure the smooth and reliable rotation.
Further, according to the chain lever hoist of the illustrated embodiment, since the first hub
55
and the second hub
39
are threadedly engaged with the screw-thread portion
50
of the drive shaft of substantially equal in diameter and also the axial movement of the second hub
39
threadedly engaged with the screw-thread portion
50
is limited by the stop member
54
fitted in the fitting groove
51
, reliable free rotation operation can be ensured, while also rigidity of the drive shaft
37
can be increased. In other words, for example in a case where the drive shaft
37
is splined at a portion thereof for mounting the second hub
39
thereon and is threaded at a portion thereof for mounting the first hub
55
, the drive shaft will inevitably be reduced in rigidity and durability. This is because since the second hub
39
must be mounted first prior to the mounting of the first hub
55
in the assembling work, the threaded portion of the drive shaft cannot help being made smaller in diameter than the splined portion and also a portion of the drive shaft extending between the splined portion and the threaded portion cannot help being made smaller in diameter than those portions for the machining need. The arrangement of the invention in which the first hub
55
and the second hub
39
are both threadedly mounted on the screw-thread portion
50
of substantially equal in diameter and also the stop member
54
is fitted in the fitting groove
51
, so that the first hub
55
can be screwed forward and backward along the drive shaft
37
and also the second hub
39
can be non-rotatable relative to the drive shaft
37
can provide increased rigidity of the drive shaft
37
and thus improved durability of the chain lever hoist.
While the illustrative embodiments of the present invention is provided in the above description, such is for illustrative purpose only and it is not to be construed restrictively. Modification and variation of the present invention that will be obvious to those skilled in the art is to be covered in the following claims.
Claims
- 1. A chain lever hoist comprising:a load sheave with which a load chain is engaged; a first hub forming engaging teeth around an outside thereof; an operating lever having an engaging pawl selectively engageable with the engaging teeth and loosely fitted around the outside of the first hub; a mechanical brake comprising a second hub interposed between the first hub and the load sheave, an anti-reverse gear supported on the second hub, two brake disks supported on the second hub at the opposite sides of the anti-reverse gear, and an anti-reverse pawl disposed at the outside of the anti-reverse gear and engageable with the anti-reverse gear; a reduction gear; a drive shaft, on which the first hub is threadedly mounted and with which the second hub is connected in non-rotatable relation relative thereto and onto which the load sheave is fitted, for allowing drive applied from the operating lever to be transmitted to the load sheave through the reduction gear mechanism; a biasing means, interposed between the first hub and the second hub for biasing the first hub and the second hub away from each other; an operating member fitted onto the drive shaft and mounted on the first hub; a brake cover for covering the mechanical brake, the brake cover having an opening for the first hub to be inserted therein; wherein the operating lever is rotatably supported on the brake cover at the opening thereof with a predetermined spaced interval from the first hub; wherein the operating member comprises a cylindrical base at a proximal end, an intermediate shoulder portion, and a cylindrical grip at a distal end, the base having a perimeter extending to the shoulder portion, and the base having a diameter smaller than a diameter of the cylindrical grip; wherein the operating member is mounted on the first hub in non-rotatable relation relative thereto, and a horizontal cylindrical insertion portion to insert the operating member is formed in the operating lever with a first predetermined radial spaced interval between a circumference of the base and the horizontal cylindrical insertion portion; wherein the shoulder portion is opposite a distal end of the cylindrical insertion portion at a second predetermined spaced interval and the cylindrical grip is positioned external to the cylindrical insertion portion; wherein the biasing means has a biasing force sufficient to release the pressing of the first hub against the mechanical brake when no load is applied to the load chain on a loaded side, and when the engaging pawl does not engage with the engaging teeth, so as to enable the first hub and the drive shaft to rotate together and thereby maintain a free rotation condition; and wherein the biasing force is sufficient to engage the mechanical brake when a rotation drive exceeds the contact resistance between the drive shaft and the first hub.
- 2. A chain lever hoist according to claim 1, wherein the brake cover has a brake-cover-side connecting portion for connecting the brake cover with the operating lever, the operating lever has a lever-side connecting portion for connecting the operating lever with the brake cover, the brake-cover-side connecting portion and the lever-side connecting portion being connected together by connecting means, and wherein the connecting means is arranged with a predetermined spaced interval from the first hub.
- 3. A chain lever hoist according to claim 1, wherein the connecting means comprises a holding member for holding the brake-cover-side connecting portion and the lever-side connecting portion in sandwich relation and a retaining member which is held in sandwich relation together with the brake-cover-side connecting portion and the lever-side connecting portion.
Priority Claims (1)
Number |
Date |
Country |
Kind |
10-342462 |
Dec 1998 |
JP |
|
US Referenced Citations (7)
Foreign Referenced Citations (6)
Number |
Date |
Country |
54-9381 |
Apr 1979 |
JP |
56-20986 |
Jul 1979 |
JP |
59-163298 |
Sep 1984 |
JP |
3-85389 |
Aug 1991 |
JP |
3-107490 |
Nov 1991 |
JP |
9-151084 |
Jun 1997 |
JP |