Chain lever hoist

Abstract: According to the invention there is provided a chain lever hoist comprising a main framework (1), a load sheave (2) fitted to said main framework (1) in such a way that it is able to rotate freely, a spindle (4) fitted to said main framework (1) in such a way that it rotates along with said load sheave (2), a fixed friction plate (6) secured to said spindle (4), a hub (5) screwed onto said spindle (4), a ratchet gear (7) and a plurality of brake linings (8) fitted onto said spindle (4) such that they are able to rotate and slide freely between said fixed friction plate (6) and said hub (5), a plurality of ratchet pawls (7a) fitted to said main framework (1) such that they engage said ratchet gear (7), and a position locking mechanism (11, 5c; 12, 13, 13a, 14, 14a; 13', 15, 15, 16, 16; 17, 18, 18, 19, 19) that locks said hub (5) into a prescribed lock position in relation to said spindle (4) after it has been rotated through a few degrees from the winding operation position. The hoist of the present invention is designed to enable said hub (5) which screws freely onto said spindle (4) in the conventional manner, to be rotated through a few degrees into a prescribed lock position relative to said spindle (4) and then locked there either temporarily or permanently as required. Hereby a major drawback of the commonly used hoists of the kind referred to above is overcome. This drawback resides in the fact that, if the chain is drawn quickly over the load sheave (2) while it is set for free running operation, the brake will automatically be applied and the free running movement terminated. Similarly, if a light load is suspended from the chain, the weight of the load may be insufficient to activate to brake with the result that the load will be wound down dangerously quickly, leading on occasion to accidents.

Description: The invention relates to a chain lever hoist (hereafter abbreviated as "lever hoist") according to the preamble of claim 1. A chain lever hoist of the kind referred to above is known from US-A- 3 047 114. According to the disclosure of US-A-3 047 114 the chain lever hoist may be brought in a position for free running operation, in which however, the associated parts, namely hub, spindle, friction plate, brake linings and ratchet gear are free running, but the positions thereof may inadvertently changed resulting in indefinite positions of these associated parts relative to each other, so that the braking function may be activated even in this specified position for free running operation. Spring lever hoists in general suffer from a significant drawback, in that when the chain is moved quickly while the load sheave is in free running operation, the spindle turns but the hub does not turn with it and, since the spindle and the hub are linked by a threaded connection, the spade between a fixed friction plate and a hub is automatically narrowed and a brake applied, thereby eliminating the capacity for free movement. The hub thus has to be rotated manually back each time this happens in order to re-open the gap between the hub and the fixed friction plate and release the brake From DE-C-0 976 683 there is known a lever hoist having free running means which contains spring means for pressing the hub outwards. Another problem arises with this type of spring lever hoist in so far as, when winding down a light object, the force with which the spindle is being screwed into the hub is sometimes weaker than that with which the coil spring is pressing the hub outwards. In this case, the object being lowered is sometimes let down too quickly and this has in the past led to accidents, some of which have been fatal. In other words, conventional spring lever hoists have what we might call a reciprocal problem in that, if the coil spring is fairly powerfully extended, this will ensure that there is plenty of play in the hub and spindle but there will also be a risk that light objects may be lowered too quickly, leading to accidents. On the other hand, if the spring is only weakly extended, this will help prevent accidents when lowering light objects but, conversely, any rapid movement of the chain while running freely over the load sheave will immediately cause the brake to operate, thus interfering with the free movement of the chain. There are, of course, a variety of mechanisms (see for instance US-A-5 088 694) that can be used to ensure the free running of a load sheave. These include a mechanism whereby, in lever hoists equipped with reduction gears of the type referred to above, the reduction gear spindle can be caused to slide as a means of shifting the gear teeth out of line with each other, thereby permitting the load sheave to rotate freely. Another mechanism disconnects the pawl from the ratchet gear and this again has the effect of allowing the load sheave to rotate freely. The use of these types of mechanism certainly helps to prevent the sorts of problems outlined above but, at the same time, the complexity of these mechanisms can in itself be a source of problems in that the smooth operation of the apparatus is rendered more problematic. There is also a concomitant loss of reliability in that the apparatus tends to break down more often. Moreover, the change from a free running to a winding action always requires a single action. The main object underlying the present invention is to overcome the above described problems inherent in the prior art and to provide a chain lever hoist, which render such a chain lever hoist more safe and do surely avoid any activation of the brake mechanism under the free running operation condition. According to the present invention there is provided a chain lever hoist as set out in claim 1. According to characterizing features thereof at first a knob is set to a neutral position to enable the hub to be rotated from a position for winding operation in a prescribed position for free running operation. Thus the user must intend to enable the free running operation of the chain lever hoist and thus a knob will be handled and brought into a predetermined neutral position thereof. On the second hand the hub will be rotated from a position for winding operation in only one direction to the prescribed position for free running operation. After the hub has been rotated through a few degrees in this only one direction and will be placed in the prescribed position for free running operation, the position locking mechanism according to the present invention will come into effect. This position locking mechanism is designed in such a way that the hub will be locked in relation to the spindle in a position away from the first friction plate and the brake linings and furtheron this position locking mechanism will hold the spindle and the hub in these fixed positions relative to each other. Thus the design of the position locking mechanism is arranged in such manner that a contact pressure of the hub on said ratchet gear and said brake linings is prevented, so that the load sheave can rotate without any risk that a braking effect will occur or the brake will be applied. The position locking mechanism of the chain lever hoist of the present invention is not used for locking different operation positions, but this position locking mechanism is only effective in the prescribed position for free running operation of the chain lever hoist. This position locking mechanism thus clearly fixes and holds the spindle and the hub in such relativ positions to each other that the friction plate and the brake linings are spaced away from one another in order to reliably avoid an inadvertent activation and applying of the brake built into the chain lever hoist. Since the chain lever hoist of the present invention completely and positively eliminates any activation of the brake mechanism in the prescribed position for free running operation it is ascertained that the load sheave can spin freely and quickly without activating the brake and the hub cannot exert a contact pressure on the ratchet gear and the brake linings. Thus it is avoided that an object may be lowered too quickly which will lead to accidents, some of which have been fatal. On the second hand the associated parts of the chain lever hoist are definitely positioned in such a manner that also the free running operation may be realized without any troubles and failure, since these are held in fixed positions relative to each other in the prescribed position for free running operation and are spaced away from each other in such a manner that the brake mechanism cannot be activated which may cause troubles during the intended use of the free running operation condition of the chain lever hoist. It is possible, therefore, in the lever hoist of the present invention, to create a space between the fixed friction plate and the hub by shifting the hub into a prescribed lock position in which the contact pressure on the ratchet gear and brake linings is released and then using a position locking mechanism to set the hub in said prescribed lock position such that the spindle and the hub are then held in positions relative to each other in which the brake will not be activated, thereby enabling the apparatus to run freely and steadily without any risk that the brake will be activated before the operation is completed. Again, since, there is no coil spring or associated parts maintaining constant outward pressure on the hub, when the aforementioned position locking mechanism is released, the hub will immediately exert contact pressure on the ratchet gear and brake linings with the result that the danger of light loads being wound down dangerously quickly through failure to activate the brake mechanism is completely eliminated. Furthermore, if the holding strength of the position locking mechanism is set to a level less than that of the torque applied to the hub to wind the load chain up, the winding function of the apparatus can be activated simply by initiating the winding action. Preferred embodiments of the present invention are subject matters of claims 2 to 13. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a vertical sectional view of the principal mechanism of the first embodiment of the invention. Figure 2 is a partial front view of the first embodiment of the invention showing the relative positions of the hub, spindle and associated parts during a winding operation. Figure 3 is a partial front view of the first embodiment of the invention showing the relative positions of the hub, spindle and associated parts when the mechanism is set for free running. Figure 4 is a sectional view taken along lines IV-IV of Figure 2. Figure 5 is a sectional view taken along lines V-V of Figure 3. Figure 6 is a view of the second embodiment of the invention shown during a winding operation, said view corresponding in all other respects to the view of the first embodiment of the invention shown in Figure 2. Figure 7 is a view of the third embodiment of the invention shown during a winding operation, said view corresponding in all other respects to the view of the first embodiment of the invention shown in Figure 2. Figure 8 is a view of the third embodiment of the invention shown when the mechanism is set for free running, said view corresponding in all other respects to the view shown in Figure 3. Figure 9 is a view of the fourth embodiment of the invention shown during a winding operation, said view corresponding in all other respects to the view of the first embodiment of the invention shown in Figure 2. Figure 10 is a view of the fourth embodiment of the invention shown when the mechanism is set for free running, said view corresponding in all other respects to the view shown in Figure 3. Figures 11 is a view of the fifth embodiment of the invention shown during a winding operation, said view corresponding in all other respects to the view of the first embodiment of the invention shown in Figure 2. Figure 12 is a view of the fifth embodiment of the invention shown when the mechanism is set for free running, said view corresponding in all other respects to the view shown in Figure 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Figures 1 through 5 illustrate the first embodiment of the invention. In Figure 1, 1 is the main framework, 2 is a load sheave fitted to the main framework 1 in such a way as to enable it to rotate freely, 3 is a load chain which loops over said load sheave 2, 4 is a spindle which is fitted to the main framework 1 in such a way as to enable it to rotate freely and which also has a threaded section 4a at one end and a spindle gear 4b at the other end, said spindle gear 4b engaging the load sheave 2 gear 2a through the medium of a set of reduction gears G. 5 is a disc-shaped hub with a threaded hole in the center into which is screwed the externally threaded section 4a of the aforementioned spindle 4. Said hub 5 incorporates a friction plate 5b, a switch gear 5a and a boss 5c on the outer surface. In this case, the outer surface of the hub 5 also acts as a knob to enable the manual rotation of the hub 5. This knob could just as easily be made entirely separate and subsequently fitted to the outer surface of said hub 5. 6 is a fixed friction plate secured to the spindle 4. A ratchet gear 7 and one or more brake linings 8 are mounted in such a way as to allow them to rotate and slide freely on the spindle 4 in between the aforementioned friction plate 5b and the fixed friction plate 6. The ratchet gear 7 and the brake linings 8 can be tightened or eased by rotating the hub 5 manually in order to vary the size of the gap between the fixed friction plate 6 and said hub 5. Also in Figure 1, 7a is a pair of ratchet pawls that are fitted to the main framework 1 and that engage the aforementioned ratchet gear 7, and 9 is a lever that is fitted in such a way that it pivots about the spindle 4. 10 is a knob for switching between a winding operation and a free running operation, which is fitted to the lever 9 in such a way as to enable it to rotate freely and which has a U shaped switch claw 10a on its inside end that engages the aforementioned switch gear 5a of the hub 5. 11 is a plate spring shaped like a fan, as shown in Figure 2, and secured to the spindle 4 in such a way that it is able to rotate around said spindle 4, said plate spring 11 and the aforementioned boss 5c together comprising a position locking mechanism. Figure 2 shows a condition in which the hub 5 has been rotated in a clockwise direction to screw it onto the spindle 4. In this condition, the boss 5c makes pressure contact with the plate spring 11, as shown in Figure 4, in such a way that boss 5c is able to slide against said plate spring 11. Figure 3 shows the hub 5 moved manually counterclockwise through a few degrees and then set at a prescribed lock position. The counterclockwise movement of the hub serves to disengage the boss 5c from the plate spring 11, as shown in Figure 5, and allows it to come to rest against the counterclockwise edge of said spring 11, thereby temporarily preventing the hub from rotating back in a clockwise direction. Next, we will describe the basic operation of a lever hoist configured in the manner outlined above. When carrying out an upward winding operation, first the aforementioned knob 10 is flipped in a clockwise direction so that the left hand tooth of the switch claw 10a, shown in Figure 2, engages the switch gear 5a. If the aforementioned lever 9 is now rotated in a clockwise direction, the combination of the weight of the suspended load and the torque applied by said lever 9 will cause the hub 5 to screw onto the spindle 4 and, in so doing, to squeeze the aforementioned ratchet gear 7 and brake linings 8 between the hub 5 and the fixed friction plate 6. At this point, the boss 5c is in pressure contact with the plate spring 11 as shown in Figures 2 and 4. If the aforementioned lever 9 is now turned repeatedly in a clockwise direction, the turning force will be transmitted from the hub 5 through the ratchet gear 7, the brake linings 8, the fixed friction plate 6 and the spindle 4 to the load sheave 2 and, as the ratchet gear 7 turns, riding repeatedly up over the ratchet pawls 7a, so the load sheave 2 will also rotate and wind up the load chain 3. When carrying out a downward winding operation, on the other hand, first the aforementioned knob 10 is flipped in a counterclockwise direction so that the right hand tooth of the switch claw 10a, shown in Figure 2, engages the switch gear 5a. The torque generated by the suspended load will again cause the hub 5 to screw onto the spindle 4 and, in so doing, to squeeze the aforementioned ratchet gear 7 and brake linings 8 between the hub 5 and the fixed friction plate 6. At this point, the boss 5c is again in pressure contact with the plate spring 11. However, if the aforementioned lever 9 is now turned repeatedly in a counterclockwise direction, as it turns, the torque generated by the lever 9 will be sufficient to mitigate the squeezing force described above and, in this way, to allow the fixed friction plate 6 on the one hand and the aforementioned ratchet gear 7 and brake linings 8 on the other sufficient freedom to slide against each other, thereby enabling the load sheave 2 to rotate and wind down the load chain 3. When the chain is to be allowed to run freely over the load sheave, the knob 10 is first set to the neutral position, as shown in Figure 3, in order to disengage the switch claw 10a from the switch gear 5a and enable the hub 5 to be manually rotated counterclockwise through a few degrees and temporarily secured in the prescribed lock position. In other words, the boss 5c has been disengaged from the plate spring 11, as shown in Figures 3 and 5, and has come to rest against the counterclockwise edge of said spring 11, thereby preventing the hub from rotating back in a clockwise direction. In this position, the contact pressure of the hub 5 on the the ratchet gear 7 and the brake linings 8 is eased and the spindle 4 and the hub 5 are held in fixed positions relative to each other, thereby preventing the brake from being applied. This has the effect of allowing the load sheave 2 to rotate freely and, at the same time, of preventing the brake from being applied even if the load sheave 2 is spun round quickly. Again, since there is no coil spring or associated parts maintaining constant outward pressure on the hub 5, as would be the case with a conventional spring lever hoist, when the temporary lock secured by means of the aforementioned position locking mechanism is released, the hub 5 will immediately reassert contact pressure on the ratchet gear 7 and brake linings 8 with the result that the danger of light loads being wound down dangerously quickly through failure to activate the brake mechanism is completely eliminated. When switching back from a free running operation to a winding operation, if the knob 10 is flipped in a clockwise direction so as to cause the left hand tooth of the switch claw 10a to engage the switch gear 5a and the aforementioned lever 9 is then wound in a clockwise direction, the torque generated by said lever 9 will exceed the force exerted by the plate spring 11 to prevent the boss 5c from moving and said boss 5c will force the plate spring 11 upwards, thereby allowing the hub 5 to rotate back in a clockwise direction to return to the condition illustrated in Figure 2. With the mechanism in this condition, the winding operation can be started immediately. Next, we will describe the second, third and fourth embodiments of the invention. In these alternative embodiments, the differences from the first embodiment are confined in each case to the position locking mechanism. Figure 6 shows the second embodiment of the invention. In the first embodiment, the plate spring 11 was shaped like a fan pivoting about the spindle. In the second embodiment, by contrast, the plate spring 11' is shaped like a disc centered on the spindle and containing a single narrow groove 11'a cut in a radial direction from part way along an imaginary line extending from the center of rotation of the spindle. In other words, Figure 6 illustrates a condition in which the hub 5 has been screwed in a clockwise direction onto the spindle 4 and the boss 5c is in pressure contact with the plate spring 11'. If the hub 5 is then manually rotated counterclockwise through a few degrees, the boss 5c slips into the groove 11'a in the plate spring 11', thereby preventing the hub 5 from rotating back in a clockwise direction and, in so doing, temporarily locking the hub 5 in its prescribed lock position relative to the spindle 4. Figures 7 and 8 illustrate the third embodiment of the invention. In this embodiment, the outer surface of the hub 5 incorporates an indented section 12 within which a disc 13 is also secured to the spindle 4, the circumference of said disc 13 containing a notch 13a. The indented section 12 is also fitted with a bar spring 14 with a U shaped projection 14a part way along, said bar spring 14 being secured at one end to the inside circumference wall of the indented section 12 such that the projection 14a of the bar spring 14 presses on the outer edge of the disc 13. Figure 7 shows the hub 5 screwed onto the spindle 4 in a clockwise direction such that the projection 14a is pressing on the outer edge of the disc 13. Next, in Figure 8, the hub 5 has been manually rotated counterclockwise through a few degrees such that the projection 14a has now slotted into the notch 13a on the circumference of the disc 13 with the result that the hub 5 cannot now be rotated further and the hub 5 and spindle 4 are thus temporarily locked into their prescribed lock positions relative to each other. For the purposes of the present embodiment, we have assumed that the bar spring 14 is secured at one end only to the inside circumference wall of the indented section 12, but the bar spring 14 could equally be secured in this same way at both ends. Figures 9 and 10 illustrate the fourth embodiment of the invention. In this embodiment, the outer surface of the hub 5 incorporates an indented section 12 within which a disc 13' is also secured to the spindle 4, the circumference of said disc 13' being fitted with a pair of cylinders 15,15 projecting outwards from the edge of the disc in diametrically opposite directions. The outer tip of each cylinder 15 is fitted with an ball embedded on the end of a compressed coil spring contained within the main body of each cylinder 15. The inside circumference wall of the indented section 12 incorporates two notches 16,16 also diametrically opposite each other. Figure 9 shows the hub 5 screwed onto the spindle 4 in a clockwise direction such that the balls embedded in each cylinder 15 are pressing on the inside circumference wall of the indented section 12 of the hub 5. Next, in Figure 10, the hub 5 has been manually rotated counterclockwise through a few degrees such that the balls embedded in the cylinders 15,15 have now slotted into the notches 16,16 in the indented section 12 with the result that the hub 5 cannot now be rotated further and the hub 5 and spindle 4 are thus temporarily locked into their prescribed lock positions relative to each other. Figures 11 and 12 illustrate a fifth embodiment of the invention. In embodiments 1 to 4, springs or similar devices were used to hold the hub and spindle temporarily in their fixed positions relative to each other. In the fifth embodiment of the invention, by contrast, when the hub and spindle are shifted into their relative fixed positions, they are then clamped securely into those positions. In other words, in this case, 17 is a cap which is spline jointed in such a way that it can move only in an axial direction in relation to the spindle 4. On the back of said cap 17, there are two rods 18,18 positioned diametrically opposite each other. There are also two holes 19,19 similarly positioned diametrically opposite each other in the side of the hub 5. Figure 11 shows the hub 5 screwed clockwise onto the spindle 4 in such a way that the rods 18,18 and the holes 19,19 are out of alignment with each other. Next, in Figure 12, the hub 5 is shown after manual rotation counterclockwise through a few degrees such that the rods 18,18 slot into the holes 19,19, thereby preventing the hub 5 from turning further and effectively securing it firmly in its prescribed lock position in relation to the spindle 4. There is also a coil spring (not shown in the drawings) fitted in between the hub 5 and the cap 17 such that the cap 17 is constantly being pulled in the direction of the hub 5. The coil spring also acts as a torsion spring in that it is constantly trying to screw said cap 17 round in a clockwise direction. Thus, when the user wants to return the apparatus from a free running operation as shown in Figure 12 to a winding operation, he needs only pull the cap 17 forward and it will immediately snap back into the winding operation position illustrated in Figure 11. As will be clear from the above, one of the essential characteristics of this invention is that, in order to maintain the free running operation of the load sheave 2, it ensures that the positions of the hub 5 and the spindle 4 can be fixed either permanently or temporarily in relation to each other so that they then rotate together in line with the movement of the load chain 3. One of the merits offered by the first four embodiments of the invention is that, since the position locking mechanism exerts only a fairly weak temporary holding force on the apparatus, any application of a specified level of external force in the form of, for example, the lever 9 torque will be sufficient to break the hold of the locking mechanism and effectively make the apparatus immediately ready for a winding operation. There is no need for the position locking mechanisms of the invention to be confined to those described in connection with the embodiments outlined above and any mechanism that serves to lock the hub either temporarily or permanently in position after it has been rotated manually through a few degrees into its prescribed lock position would be acceptable. The wide variety of mechanisms that could conceivably serve this sort of purpose has not been illustrated or described in the body of the text. There is equally no reason why the hub and spindle structures of the invention should necessarily be different from conventional hub and spindle structures. The hub, for example, could be structured in accordance with convention and the pitch of the spindle thread could be made to increase gradually in size towards the outer end of the spindle, unlike a conventional spindle. In this sort of case, when the hub is manually rotated along the spindle, it will inevitably catch on the unusually formed part of the spindle and, in this way, become temporarily locked.

Claims: A chain lever hoist comprising: a main framework (1), a load sheave (2) fitted to said main framework (1) in such a way that it is able to rotate freely, a chain (3) capable of being wound around said load sheave (2), a spindle (4) fitted to said main framework (1) in such a way that it rotates along with said load sheave (2), a first fixed friction plate (6) secured to said spindle (4), a hub (5) screwed onto said spindle (4), a ratchet gear (7) and a plurality of brake linings (8) fitted onto said spindle (4) such that they are able to rotate and slide freely between said first fixed friction plate (6) and said hub (5), a plurality of ratchet pawls (7a) fitted to said main framework (1) such that they engage said ratchet gear (7), and a position locking mechanism (11, 5c; 11', 11'a, 5c; 12, 13, 13a, 14, 14a; 13', 15, 16, 17, 18, 19) characterized in that a knob (10) can first be set to a neutral position to enable said hub (5) to be rotated from a position for winding operation in a prescribed position for free running operation and after said hub (5) has been rotated from said position for winding operation in only one direction to said prescribed position for free running operation said position locking mechanism (11, 5c; 11', 11'a, 5c; 12, 13, 13a, 14, 14a; 13', 15, 16, 17, 18, 19) is adapted to lock said hub (5) in relation to the spindle (4) away from said first friction plate (6) and said brake linings (8) in said position for free running operation and to hold said spindle (4) and said hub (5) in fixed positions relative to each other for preventing contact pressure of said hub (5) on said ratchet gear (7) and said brake linings (8) and allowing said load sheave (2) to rotate while preventing a brake from being applied. A chain lever hoist according to claim 1, further comprising a plurality of reduction gears (G) such that said load sheave (2) und said spindle (4) are linked through said plurality of reduction gears (G). A chain lever hoist according to anyone of the preceding claims, wherein said hub (5) comprises a friction plate (5b) facing said brake lining (8), a switch gear (5a) facing said friction plate (6) and a disc portion facing away from said switch gear (5) which functions as a knob (10). A chain lever hoist according to claim 3, further comprising a lever (9) fitted onto said spindle (4) in such a way as to enable said lever (9) to pivot freely about said spindle (4), and a switch claw (10a) fitted to said lever (9) such that said hoist can be maneuvered selectively between an upward winding position, in which said lever (9) engages said switch gear (5a) so that said lever (9) rotates in a first direction, a downward winding position, in which said lever (9) engages said switch gear (5a) so that said lever (9) rotates in a direction opposite said first direction, and a neutral position, in which said lever (9) remains out of contact with said switch gear (5a), and in which when said switch claw (10a) in set to said neutral position, said position locking mechanism (11, 5c; 11', 11'a, 5c) holds said hub (5) in a prescribed lock position relative to said spindle (4). A chain lever hoist according to anyone of the preceding claims, wherein said brake linings (8) are fitted to both sides of said ratchet gear (7). A chain lever hoist according to anyone of the preceding claims, wherein said position locking mechanism (11, 5c; 11', 11'a, 5c) comprises a boss (5c) fitted to said hub (5), and a plate spring (11; 11') which is secured to said spindle (4) and which is being designed to press on said boss (5c) during said winding operation and to clamp said boss (5c) during said free running operation. A chain lever hoist according to claim 6, wherein said plate spring (11) is fan-shaped and is capable of pivoting about a center of rotation of said spindle (4), and an edge of said plate spring (11) rests against said boss (5c) during said free running operation, thereby holding said hub (5) temporarily in said lock position in relation to said spindle (4). A chain lever hoist according to claim 6, wherein said plate spring (11') is disc-shaped having a narrow-cut radial groove (11'a) which does not extend to said spindle (4), such that said boss (5c) is trapped in said groove (11'a) during said free running operation, thereby holding said hub (5) temporarily in said lock position in relation to said spindle (4). A chain lever hoist according to anyone of the preceding claims 1 to 5, wherein said position locking mechanism comprises a disc (13) having a notch (13a) in an outer edge and in secured to said spindle (4), and a spring bar (14) having a U-shaped projection (14a) and in secured at one end to said hub (5), said projection (14a) being out of alignment with said notch (13a) in said disc (13) during said winding operation and slotted in said notch (13a) during said free running operation in order to hold said hub (5) temporarily in said lock position in relation to said spindle (4). A chain lever hoist according to claim 10, wherein both ends of said spring bar (14) are secured to said hub (5). A chain lever hoist according to anyone of the preceding claims 1 to 5, wherein said position locking mechanism comprises a plurality of notches (16) set into an indented section (12) in an outer surface of said hub (5), and a plurality of cylinders (15) secured in opposing radial alignment to said spindle (4), said cylinders (15) each containing an embedded ball and a coil spring pressing said ball outwards from an end of said cylinders (15) and in which said balls remain out of alignment with said notches (16) in said hub (5) during said winding operation and slip into said notches (16) in said hub (5) during said free running operation, thereby holding said hub (5) temporarily in said lock position in relation to said spindle (4). A chain lever hoist according to anyone of the preceding claims 1 to 5, wherein said position locking mechanism comprises a cap (17) which is spline connected such that said cap (17) can only move in an axial direction in relation to said spindle (4) and which has a plurality of rods (18, 18) secured to an inner surface of said cap (17) and a plurality of holes (19) in the surface of said hub (5), and in which said rods (18) remain out of alignment with said holes (19) in said hub (5) during said winding operation and slot into said holes (19) in said hub (5) during said free running operation, thereby holding said hub (5) temporarily in said lock position in relation to said spindle (4). A chain lever hoist according to anyone of the preceding claims, wherein a plurality of ratchet pawls (7a) fitted to said main framework (1) such that they engage said ratchet gear (7).

Inventors: KATAOKA IWAO, KATAOKA, IWAO
Applicants: HHH MFG CO, H.H.H. MANUFACTURING CO.
Application year: 1993
Main classification: B66D3
IPC codes: B66D3