LIFTING GEAR

Abstract

A lever hoist includes a housing in which a load chain wheel and a drive shaft driving the load chain wheel via a transmission are rotatably mounted, as well as a safety brake. A load chain is movable via the load chain wheel. The safety brake implements emergency braking in response to excessive rotational speed of the drive shaft. The safety brake includes a locking disc with teeth and a control disc with control cams. The locking disc and the control disc are rotatable in a limited manner. A catch hook is movable in a swivelling manner and has a latch contour at a front end and a sensing contour at a rear end. The sensing contour rests on the control disc. When a defined rotational speed is exceeded, the sensing contour lifts off the control disc. The latch contour engages with a locking tooth of the locking disc.

Claims

1. Lifting gear, particularly a lever hoist, comprising a housing, in which a load chain wheel and a drive shaft are supported in the load chain wheel driven via a transmission such that it can rotate, as well as a drive, a load pressure brake and a safety brake, in which a load chain can be moved via the load chain wheel, wherein the safety brake exhibits a locking disc with locking teeth and a control disc with control cams and a catch hook, wherein the locking disc and the control disc can be rotated in relation to each other, wherein the rotation is limited by a rotation limiter and wherein the catch hook is arranged so that it can be moved in a swivelling manner and exhibits a latch contour on a front end and a sensing contour on a rear end, wherein the sensing contour rests under the effect of the spring element on the control disc and the latch contour can be brought to engage lockingly with a locking tooth of the locking disc.

2. Lifting gear according to claim 1, wherein the rotation limier exhibits at least one curved track and a stopper, which can be displaced along the curved track.

3. Lifting gear according to claim 2, wherein that curved track is formed by a slot or a groove in the control disc or the locking disc.

4. Lifting gear according to claim 2, wherein the stopper is a pin.

5. Lifting gear according to claim 1, wherein ratchet elements are incorporated between the locking disc and the control disc.

6. Lifting gear according to claim 1, wherein several locking teeth are arranged uniformly distributed on the circumference of the locking disc.

7. Lifting gear according to claim 1, wherein several locking cams are arranged uniformly distributed on the circumference of the control disc.

8. Lifting gear according to claim 1, wherein the control disc exhibits a central support provided with an internal toothing, on which the locking disc is positioned with a central supporting section and is secured in position by a securing element.

9. Lifting gear according to claim 1, wherein in the starting position of the locking disc and control disc the rear external contour of the locking teeth is flush with the external contour of the control disc.

10. Lifting gear according to claim 1, wherein the catch hook is supported on a side plate that can be incorporated into the housing.

11. Lifting gear according to claim 1, wherein a release for resetting the locking disc and control disc in their starting position is provided.

12. Lifting gear according to claim 1, wherein a return lock is provided, which prevents a rotation of the locking disc and control disc in their starting position.

Description

[0030] The invention is explained in more detail in the following using the drawings. They indicate as follows:

[0031] FIG. 1 shows lifting gear according to the invention in the form of lever hoist in a longitudinal section;

[0032] FIG. 2 shows the lever hoist in an explosion illustration of its components;

[0033] FIG. 3 shows a side view of a part of the lever hoist;

[0034] FIG. 4 shows a perspective view of the safety brake of the lever hoist;

[0035] FIG. 5 shows a perspective view of the locking disc and control disc of the safety brake;

[0036] FIG. 6 shows components of the safety brake in an explosive form of illustration;

[0037] FIG. 7 shows a view from above of the illustration of FIG. 5;

[0038] FIG. 8 shows a cross-section through the illustration of FIG. 7 along line A-A;

[0039] FIG. 9 shows a cross-section through the illustration of FIG. 7 along line B-B;

[0040] FIG. 10 shows the illustration according to FIG. 5 in a view from below;

[0041] FIG. 11 shows the open lever hoist with a view in the region of the load pressure brake and the safety brake in a normal situation;

[0042] FIG. 12 shows the illustration according to FIG. 11 in a problem situation;

[0043] FIG. 13 shows a view of the safety brake of the lever hoist in a first operating situation;

[0044] FIG. 14 shows the safety brake in a second operating situation;

[0045] FIG. 15 shows the safety brake in a third operating situation;

[0046] FIG. 16 shows the safety brake in a fourth operating situation;

[0047] FIG. 17 shows the illustration of the safety brake in an unlocking process for resetting the locking disc and control disc in their starting position;

[0048] FIGS. 18 to 23 show a second illustrative embodiment of safety brake with a return lock.

[0049] FIGS. 1 and 2 show a piece of lifting gear according to the invention in the form of a manually-operated lever hoist 1. A component of the lever hoist 1 is a housing 2 which is composed of several housing parts 3, 4 and side plates 5, 6 and distance frame 7. The lever hoist 1 is characterised by a supporting hook 8 as an upper fastening element and load hook 9 as a lower slinging element. The supporting hook 8 and the load hook 9 are directly interconnected via the housing 2. The load hook 9 is slung onto one end of a load chain 10. A chain end piece 11 is provided at the other end of the load chain 10. Via a drive for the means of traction, the load chain 10 can be moved. The drive for the means of traction essentially comprises a drive 12 with a hand lever 13, a ratchet wheel 14 and a shiftable ratchet mechanism 15, a load pressure brake 16, a load chain wheel 17 and a transmission 18. The hand lever 13 and the ratchet wheel 14 of the ratchet mechanism 15 sit on the end 19 of a drive shaft 20 which press home the load pressure brake 16 and the load chain wheel 17. On the other end 21 of the drive shaft 20 is located the transmission 18, which is connected to the load chain wheel 17 in such as way as to transfer torque. A hand wheel 22 is used to displace the ratchet wheel 14 axially on the drive shaft 20, to operate a free-running mechanism 23 of the lever hoist 1.

[0050] On its external circumference, the load pressure brake 16 exhibits a ratchet wheel disc 24 provided with teeth. On both sides, the ratchet wheel disc 24 is provided with friction elements 25 in the form of friction pads. Furthermore, the load pressure brake 16 exhibits two pawls 26 supported in the housing 2 on the side plate 6 such that they can swivel, which are compressed under the effect of locking hook springs 27 onto the ratchet wheel disc 24. Furthermore, a pressure disc 28, on which the ratchet wheel disc 24 is supported, which forms part of the load pressure brake 16. The ratchet wheel 14 can be displaced axially on a movement thread 29 of the drive shaft 20. FIG. 3 shows the lever hoist 1 with ratchet wheel 14, hand lever 13 and hand wheel 22 removed.

[0051] The load pressure brake 16 has the task of holding the load supported by the lever hoist 1 when the ratchet wheel 14 is stationary. Then the ratchet wheel 14 is pressed over the ratchet wheel disc 24 and the integrated friction elements 25 are pressed onto the compression disc 28. The pawls 26 are located in the circumferential recesses of the ratchet wheel disc 24. If the ratchet wheel 14 is rotated in the lifting direction, the pawls 26 slide over the teeth of the ratchet wheel disc 24 until the ratchet wheel 14 comes to a stop. Then the pawls 26 are resting in the recess of the ratchet wheel disc 24 again. When lowering the load, the ratchet wheel 14 is rotated in the opposite direction, by which it slides axially on the movement thread 29 of the drive shaft 20 and the frictionally engaged contact with the friction elements 25 of the ratchet wheel disc 24 and the compression disc 28 is raised. The load can then be lowered until the drive shaft 20 that continues to rotate compensates for the axial backlash again.

[0052] In addition to the standard load pressure brake 16, the lever hoist 1 exhibits a safety brake 30, 31. The safety brake 30, 31 has the task of undertaking emergency braking in extreme situations in which there is so high a rotational speed of the drive shaft 20 that the load pressure brake 16 no longer engages due to inertia.

[0053] A safety brake 30 and its operation are described with reference to FIGS. 4 to 17. A second illustrative example of a safety brake 31 is explained using FIGS. 18 to 23. Components or sub-components corresponding to each other are provided with the same reference number. The safety brake 30, 31 is arranged in the direction to the load chain wheel 17 co-axially underneath or behind the load pressure brake 16.

[0054] The safety brake 30, 31 exhibits a locking disc 32 with locking teeth 33 and a control disc 34 with control cams 35 as well as a catch hook 36. On the circumference of the locking disc 32 several locking teeth 33, three in the illustrative example, are arranged uniformly distributed. The control disc 34 is configured in a triangular shape with the control cams 35 formed in a rounded shape on their circumference. The control disc 34 exhibits a central support 38 provided with internal toothing 37, on which the locking disc 32 is positioned with a central storage section 39 and is secured in position by securing elements 40, 41. Via the support 38 and the internal toothing 37, the control disc 34 and with the control disc 34 the locking disc 32 is held onto a threaded section 43 of the drive shaft 20 provided with external toothing 42.

[0055] The catch hook 36 is arranged such that it can move in a swivelling manner on the side plate 5 of the lever hoist 1. By incorporating a spring element 44 in the form of a helical spring, the catch hook 36 is supported on a pin 45 on the side plate 5 and secured by a securing ring 46. The support of the catch hook 36 on the pin 45 is in the central longitudinal region of the catch hook 36 so that the catch hook 36 is supported like a see-saw.

[0056] The locking disc 32 and the control disc 34 can be rotated in relation to each other. The rotation of locking disc 32 and control disc 34 in relation to each other is limited by a rotation limiter 47. The rotation limiter 47 comprises a curved track 48 which is formed in a slot 49 in the shape of a section of a circular arc in the control disc 34. Along the curved track 48, a stopper 50 in the form of a pin can be displaced. It is recognised that three slots 49 are arranged uniformly offset in the control disc 34. Correspondingly, three pins are incorporated as stoppers 50 in the installation holes 51 of the locking disc 32. The stoppers 50 protrude in the direction of the control disc 34 compared with the locking disc 32 and engage into the slots 49. In the illustrative example shown here, the rotation limiter 47 allows a rotation of the locking disc 32 compared with the control disc 34 by 45°.

[0057] Between the locking disc 32 and the control disc 34, ratchet elements 52 in the form of steel balls are incorporated. The ratchet elements 52 fix the locking disc 32 and the control disc 34 in the starting position or in the end position after a rotation. The ratchet elements 52 are held in take-ups 53 in the control disc 34 and contact ratchet surfaces 54 that are the shape of spherical sections in the control disc 32 and act together with these as a counter bearing and inhibiting movement.

[0058] The catch hook 36 exhibits a latch contour 56 on the front end 55. The latch contour 56 exhibits a catch tooth 57 formed as a point with a catch flank 58 on the abutting side which is configuratively adapted to a front locking flank 59 of a locking tooth 33 of the locking disc 32.

[0059] On the rear end 60 a sensing contour 61 is formed on the catch hook 36. To do this, the rear end 60 of the catch hook 36 is formed of a rounded shape. With the sensing contour 61, the catch hook 36 rests under the effect of the helical spring against the outer contour of the control disc 34. The spring element 44 has the effect that in normal operation the latch contour 56 is outside the external circumference of the locking disc 32. In normal operation, the catch hook 36 slides with the rear sensing contour 61 along the control disc 34. The front latch contour is 56 is raised.

[0060] When a certain excessive rotational speed is exceeded, the sensing contour 61 of the catch hook 36 lifts as a result of the mass inertia and the acting acceleration forces of the control disc 34 or the control cams 35. The catch hook 36 tips and rotates about the pin 35 in the locking disc 32. The latch contour 56 of the catch hook 36 hooks into a locking tooth 33 of the locking disc 32 and comes to rest there with the catch flank 58 onto the locking flank 59. Consequently, the locking disc 32 is held while the control disc 34 arranged coaxially behind it continues to rotate along the specified rotation path of the rotation limiter 47. The rotation occurs until the stopper 50 comes to a stop at the end 62 of the slots 49 situated in the direction of rotation. The locking disc 32 and the control disc 34 are then locked in relation to each other. In this way, a positive-fit connection between the drive shaft 20 and the lever hoist 1 is produced. Further overrunning of the load chain wheel 17 or running out of the load chain 10 is suppressed.

[0061] FIG. 11 shows a normal situation of the load pressure brake 16 and safety brake 30. The pawls 26 engage in the ratchet wheel disc 24 and hold the load.

[0062] FIG. 12 shows a problem situation. The pawls 26 of the load pressure brake 16 are not free running. The pawls 26 do not engage into the ratchet wheel disc 24. A load cannot be held. A dangerously excessive speed compared with the pulling direction of the lever hoist 1 may occur associated with the load chain 10 running out.

[0063] FIGS. 13 and 14 shows the safety brake 30 respectively in a normal situation or starting position. The locking disc 32 and the control disc 34 are designed to be flush so that the rear external contour of the locking teeth 33 are covered with the external contour of the control disc 32. The sensing contour 61 of the catch hook 36 is pressed by the spring force of the helical spring against the external contour of the control disc 34 and slides along the control cams 35. The sensing contour 61 is located both in the top dead centre of the control disc 34 (FIG. 13) and in the bottom dead centre of the control disc 34 (FIG. 14) on a control cam 35. During the circulation of the control disc 34 and the locking disc 32, the front latch contour 56 of the catch hook 36 is raised out of the active region of the locking disc 32 or its locking teeth 33.

[0064] With increasing acceleration of the drive shaft 20 and with this the safety brake 30, therefore with excessive rotational speed, for example, caused by a falling load, the sensing contour 61 of the catch hook 36 is accelerated outwards and lifts from the control disc 34. The front catch tooth 57 of the latch contour 56 hooks into the locking disc 32 (see FIG. 15) and its abutting edge catch flank 58 comes to a stop lockingly on the locking flank 59 of a locking tooth 33 (see FIG. 16). After the catch hook 36 has dropped in, the control disc 34 continues to rotate driven from the load about 45° in an anticlockwise direction (arrow P1) and thus the ratchet wheel 14 locks. This effect is self-reinforcing, i.e. the deeper the catch hook 36 falls in, the greater the sensing contour 61 is raised on the opposite side by the control disc 34.

[0065] To lift the blocking of the safety brake 30 and to put the control disc 34 and the locking disc 32 back into the flush starting position, a release 63 is provided. This comprises a slider 64 for activation of the release 63 and a blocking body 66 under the effect of a tension spring 65. By operating the slider 64 (arrow P2), this locks the locking disc 32 with the blocking body 66 and holds it firmly so that the locking disc 32 is prevented from rotating, while the control disc 34 is operated in the lifting direction (clockwise) (arrow P3) via the hand wheel 22 or the hand lever 13. In this way, the locking disc 32 and the control disc 34 are displaced in relation to each other and brought into their flush starting position.

[0066] FIGS. 18 to 23 show a second illustrative embodiment of a safety brake 31. As described above, this exhibits a locking disc 32 with locking teeth 33 and a control disc 34 with locking cams 35 as well as a catch hook not shown in FIGS. 18 to 23. The catch hook corresponds to the previous explanation. The same applies to the rotation limiter and the function of the safety brake 31.

[0067] A return block 67 is provided for the safety brake 31. A return block 67 prevents a rotation of the locking disc 32 and control disc 34 in its starting position, after the safety brake 31 has triggered, therefore standing in its blocked state. The return block 67 is characterised by recesses 68 in the locking disc 32 arranged offset on a pitch circle. Clamping rollers 69 are accommodated there. The rear wall 70 of a pocket-shaped recess 68 runs inclined so that the recess 68 tapers anticlockwise. Consequently, a wedging effect arises between the locking disc 32 and the control disc 34 via the clamping rollers 69, so that the return block 67 prevents rotation of the locking disc 32 and control disc 34 in relation to each other.

[0068] It can furthermore be recognised, particularly in the illustration of FIG. 19, that a shear pin 71 is incorporated into the safety brake 31. The shear pin 71 is driven through an installation hole 72 in the locking disc 32 into an installation hole 73 in the control disc 34. The shear pin 71 prevents an undesirable triggering of the safety brake 31, for example, when pulling out manually. The shear pin 71 secures the safety brake 31 in the starting position. Only when a certain threshold is exceeded when locking the safety brake 31 is the shear pin 71 sheared off and the safety brake 31 can activate emergency braking.

REFERENCE NUMBERS

[0069] 1—Lever hoist [0070] 2—Housing [0071] 3—Housing part [0072] 4—Housing part [0073] 5—Side plate [0074] 6—Side plate [0075] 7—Distance frame [0076] 8—Supporting hook [0077] 9—Load hook [0078] 10—Load chain [0079] 11—Chain end piece [0080] 12—Drive [0081] 13—Manual lever [0082] 14—Ratchet wheel [0083] 15—Ratchet mechanism [0084] 16—Load pressure brake [0085] 17—Load chain wheel [0086] 18—Transmission [0087] 19—End of 20 [0088] 20—Drive shaft [0089] 21—End of 20 [0090] 22—Hand wheel [0091] 23—Free-running mechanism [0092] 24—Ratchet wheel disc [0093] 25—Friction element [0094] 26—Pawl [0095] 27—Ratchet hook spring [0096] 28—Compression disc [0097] 29—Movement thread [0098] 30—Safety brake [0099] 31—Safety brake [0100] 32—Locking disc [0101] 33—Locking tooth [0102] 34—Control disc [0103] 35—Control cam [0104] 36—Catch hook [0105] 37—Internal toothing [0106] 38—Support [0107] 39—Bearing section [0108] 40—Securing element [0109] 41—Securing element [0110] 42—External toothing [0111] 43—Threaded section [0112] 44—Spring element [0113] 45—Pin [0114] 46—Securing ring [0115] 47—Rotation limiter [0116] 48—Curved track [0117] 49—Slot [0118] 50—Stopper [0119] 51—Installation hole [0120] 52—Ratchet element [0121] 53—Take-up [0122] 54—Ratchet surface [0123] 55—Front end of 36 [0124] 56—Latch contour [0125] 57—Catch tooth [0126] 58—Catch flank [0127] 59—Locking flank [0128] 60—Rear end of 36 [0129] 61—Sensing contour [0130] 62—End of 49 [0131] 63—Release [0132] 64—Slider [0133] 65—Tension spring [0134] 66—Blocking body [0135] 67—Return lock [0136] 68—Recess [0137] 69—Clamping roller [0138] 70—Rear wall [0139] 71—Shear pin [0140] 72—Installation hole [0141] 73—Installation hole [0142] P1—Arrow [0143] P2—Arrow [0144] P3—Arrow