EP0692447A1

EP0692447A1 - Hoist

Info

Publication number: EP0692447A1
Application number: EP95500103A
Authority: EP
Inventors: Javier Amenabar Axpe
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-07-15
Filing date: 1995-07-13
Publication date: 1996-01-17
Anticipated expiration: 2015-07-13
Also published as: EP0692447B1; ES2116844B1; DE69520311T2; DE69520311D1; ES2116844A1

Abstract

An electric hoist (1) with an electric motor, a gear reducer and a chain (6) with a hook (7), as well as a suspension hook (2) for hanging the said hoist. A completely safe unit is presented, with a device with movable guides (24) that stops the electric motor when any of the chain links (41) are incorrectly positioned, as well as another safety device against overloads arranged on the suspension hook shaft. The unit is completed by the hoist body provided with closing covers, as well as a special bag (3) for the chain, which adjusts to the normal working position of the appliance, and also to its inverted working position.

Description

The invention relates to a hoist, of the kind which are electrically operated and use a chain to lift a load. Such hoists work alone or in combination with a transfer slide or car, which travels along a guide or profile rail.
These lifting units have an electric brake motor on whose shaft outlet is situated a gear reducer, through which movement is transmitted to a star wheel, with which the chain engages or enmeshes, with it being precisely this chain which is responsible for lifting loads by means of a hook, while also having a bag to gather up the chain.
As was mentioned previously, these hoists can operate independently by being provided with a hook or other fixing element which is secured to a fixed point, and can also be used in combination with a motorized slide or car.
These known chain hoists, which are used, as stated above, for raising and lowering all kinds of loads, are mostly powered by a instantly acting brake motor, which, at the moment it is activated, generates a magnetic field that attracts the brake block, compressing a spring and releasing the motor rotor shaft. When the motor is deactivated by means of the control or through lack of electrical power, the magnetic field disappears and, with it, the power that overcomes the effect of the spring, with the brake block automatically returning to its rest position and instantly immobilizing or locking the motor shaft.
Between the said motor and the chain wheel with recesses or star wheel, a transmission mechanism composed of a gear train or gearset is situated. Incorporated into this transmission mechanism is a torque limiter or clutch, which in turn is composed of friction discs or drivers, and this torque limiter can be adjusted by means of a nut that acts against a pack of disc springs that press up against the friction discs.
As mentioned earlier, at the end of the transmission mechanism is situated the chain wheel with recesses or star wheel, in which the recesses or support pockets for the chain are machined, with this star wheel being responsible for converting the motor rotation transmitted by the gear train into an ascending/descending linear movement of the chain.
These known hoists usually have inconveniences, disadvantages and eficiencies, some of which are of a certain consideration, in their correct operation and overall safety.
Thus, when these hoist are operating in descent, where the chain is emerging from the bag in which it is stored, this chain is operated only by its own weight and normally picks up and accumulates dry grease and dirt, which makes the links in the chain become twisted in such a way that it alters the relative position between the said links, changing them to another, incorrect, position.
This gives rise to the fact that when the said links have to enter into the guide for the chain which gives access to the star wheel, this said entrance does not correspond with the position of the link, so that if the motor continues working, the chain might be broken, given that the power of the motor is greater than the resistance of the chain.
Given also that in this case the twisted link would only work by shearing, the risk of breakage of the chain is quite considerable and this breakage sometimes takes place, with which accidents can be caused.
In another case, for instance when the hoist works with the two ends of the chain on which a sheave provided with a hook has been arranged, it is also frequent for looping to take place on the sheave itself, which creates knots or twisting in the chain.
When the chain is being gathered up, in such a way that the hook with the sheave is approaching the hoist, the initially imperceptible twisting becomes more visible as it approaches the entrance to the guides, with the circumstance that, as in the previous case, the chain can not pass through the entrance into the guide, it is placed under stress and might be broken due to the traction of the motor.
Another disadvantage of these units lies in the fact that when overloads are produced in the hoist, or when the load is immobilized by some kind of obstacle, or when a stop has been reached, the previously-mentioned torque limiter, included in the transmission mechanism, usually loses effectiveness due to the wear on the friction discs, and can even reach the point where it begins to shed its load, with the corresponding risk involved for persons, installations and equipment. Moreover, it also happens that in these situations, and in spite of the operation of the torque limiter, the motorsuffers even in its normal operation.
In the same way, problems also arise in known hoists when they work in the inverted position, as regards the passage of the hoist chain into and out of the bag.
Another disadvantage is presented by the bags in which the chain is collected, as they can not normally be used in the inverted position, making it necessary to resort to makeshift or craftsman solutions.
It is an object of the invention to provide a hoist provided with an integral safety system, with which the disadvantages and risks caused by the inappropriate positioning of the links in the chain at their entrance into the access guides to the star wheel are completely prevented, made up of a guide unit consisting of two movable guides which are situated close to the chain intake and outlet for the said access guides to the star wheel.
Another object of the invention is to provide a hoist provided with an integral safety system, which avoids the risks arising from the existence of overloads or stops which immobilize the load, by means of an overload detector mechanism.
A third object of the invention is to provide a hoist provided with specially designed main casings in order to allow the passage of the hoist chain into and out of the bag in the inverted position, and at the same time to gather and house the different components of the hoist.
A fourth object of the invention is a hoist provided with a specially-shaped bag for gathering the chain, allowing it to be used in both the normal and in the inverted working position.
To put these objectives into practice, the invention proposes a hoist with an integral safety system, in which the said hoist is assembled on a central body or casing that includes an electric brake motor and a reducer 30 gear train connected to the motor shaft outlet. The reducer gear train finishes in a shaft on which a star wheel is housed. The transmission movement or reducer gear train has a torque limiter or clutch, all in the way already known, as has been mentioned previously.
The star wheel that receives the chain is housed in the interior of a guide in which the said chain moves, and this guide can be of any known type, for example a half guide, a permanent guide or any other conventional item.
The guide in question that we are dealing with is normally provided with cross-shaped entryways to allow the chain to pass, forming the conventional inlet and output guides for the said chain in the guide.
In the present case, the invention proposes the existence of two equal parts (movable guides), arranged on any part of the hoist, either on the hoist casing itself or on the guide casing itself, with the said movable guides being kept floating on the seating area itself on the hoist casing or on the guide itself, through any kind of conventional damper or shock absorber means.
These movable guides are situated a certain distance from the cross-shaped guide entryways that are included in the hoist and are provided, in turn, with cross-shaped holes or perforations whose alignment is consistent with the said cross-shaped entryways, so that the chain which is housed in the guide passes through the movable guides.
In combination with these two movable guides, the invention provides two detector element, situated close to the guides. These detectors can be fixed either to the hoist casing or to the chain guide casing.
A portion of each of the movable guides is susceptible to make contact with or come close to the detector when a link in the chain, incorrectly aligned, forces the movable guide to alter its position and compress the damper element that it is provided with.
The detector is connected to the electrical switchboard for the hoist, so that when the movable guide changes its position and one portion of it causes the said detector to be activated, the hoist motor stops.
The detector in question can be a microswitch that operates by making contact with the portion of the movable guide; it can also be a closeness or proximity detector which is activated when the corresponding portion of the movable guide approaches a certain distance, while some other kind of conventional element can also be used.
The portions of the movable guides that activate the detector in question can form part of the casing of the parts or else can be independent parts fixed to them.
In the same way, the damper elements that keep the movable guides in position can be springs, rubber shock absorbers, Belleville discs, etc., which have the capacity to return the movable guides to their initial position when they have been moved due to the action of a badly positioned chain link. In a preferable, although non-restrictive, solution for the integral safety device, the star wheel that receives the chain is housed in the interior of a permanent guide that forms one part of the permanent guiding unit inside which the chain moves. This guide is a unit with a trapezoid or tapered elevation, of a thickness suitable for receiving the said star wheel and the said chain, while also being provided with a set of drill holes for it to be fixed to the central casing of the hoist.
On its lower side it is provided with two cross-shaped entryways for the chain to pass, which form the conventional guides, as well as a gap or cavity between the said entryways, and four holes that surround the said guides, with blind drill holes of a smaller diameter in the bases of the said holes.
Two equal parts or movable guides, secured by bolts to the lower side of the permanent guide, are kept floating by the effect of intermediate springs, forming a single unit with the permanent guide.
These two movable guides are provided with cross-shaped holes that coincide with those in the lower part of the permanent guide, which form the conventional guides, and with other holes to receive the said springs and bolts.
The holes, four for each movable guide, have an axial cross-section in the form of a double "T" and form two housings; a lower one to receive and operate the heads of the said bolts and another upper one on the side towards the permanent guide, in which some springs are received, with these springs being housed, on the other side, in the lower part of the permanent guide, in the holes provided with the previously-mentioned blind drill holes.
Springs are situated between the movable guides and the holes in the permanent guide, and the movable guides are positioned over the permanent guiding system in a floating manner by means of these springs.
The movable guides are also each provided with sidewardly protruding lugs in a prolongation of their front or forward sides, which are also aligned with each other when the two movable guides are fixed in the permanent guide by means of the said bolts and springs. A free space or gap is formed between the two lugs and the central cavity of the permanent guide, inside which two microswitches are situated, fixed to the base of the said central cavity of the permanent guide. The axial shafts of these two microswitches are aligned with the centre of the lugs on the movable guides, in which position are secured two bolts that remain a certain distance from the said microswitches.
In this situation, when the chain links are twisted or knotted, as mentioned previously, the chain can not enter through the cross-shaped gaps in the movable guides and exerts pressure on the outer surface of these said guides, causing these to oblige the springs to compress towards the permanent guide, with which the bolt of the lug on the corresponding guide makes contact with the microswitch and interrupts or breaks the electrical current and stops the motor through the electrical circuit for the hoist. Thus, the anomaly in the positioning of the links is corrected, after which the circuit is reset and normal operation of the hoist can proceed. In this way, any kind of accident caused by breakage of the chain, which would lead to the fall of the suspended load, is avoided.
As was described previously, this safeguard in case certain links do not enter into the guides is established both when the hoist is lowering a load, with the chain being paid out from the storage bag, and when it works with two chain ends or branches, which gives an idea of the integral safety that the invention provides from this point of view, on detecting any incorrect position of any link, which causes the hoist motor to stop immediately.
Taking advantage of this new form of behaviour of the hoist, it is emphasized that this circumstance can be used without the help of any kind of auxiliary item, in order to limit the raising or lowering height of the chain, by situating stops on the said chain. These stops, situated at the required points, would also make contact with the movable guides, also causing the motor to stop.
Apart from this first safety device, and that which is provided, in a conventional way, by the clutch or torque limiter arranged at the beginning of the gear reducer, the invention includes a second safety element situated on the hook and another fixing item for the hoist.
The fact that the clutch or torque limiter usually gradually loses effectiveness was mentioned earlier, and that the disadvantage also exists that the motor suffers when an overload or limit stop takes place during hoist operation.
In order to prevent these losses of performance and effectiveness, and in effect to increase the safety of the hoist, it is considered essential to incorporate an electromechanical device which, when attached to the hook or to another fixing element, cuts off the flow of electrical power to the motor when a certain overload is detected.
This second safety element is situated on the hook shaft or fixing element and consists of a damper or shock absorber unit, by placing, between this unit and nut on the hook shaft, a part provided with a side opening that receives a detector whose shaft is essentially parallel to the hook shaft. In alignment with this detector, and on the casing, is housed a bolt which is adjustable from the exterior, protected with a lid, and whose inner end juts out towards the end of the detector.
When an overload takes place in the hoist, the nut causes the shock absorber unit to become compressed and, in this travel, the part that contains the detector is moved until the detector makes contact with the end of the bolt, activating the detector and stopping the hoist drive. Obviously, the adjustment of the bolt that makes contact with the detector will provide the possibility of setting different overload limits for the appliance, as can be deduced.
The part that includes the detector is also provided with a small lug that is accommodated on one of the faces of the nut on the hook shaft or of the fixing element in order to prevent the part from turning.
This second safety element can be secured to the hook or to another fixing element for the hoist, for instance an eyebolt or similar unit and, together with the hook itself, can form an independent unit which is secured by means of bolts, by pressure, etc. to the hoist casings.
The damper or shock absorber unit can be like the one described previously or any other, for instance pressure springs, rubber shock absorbers, etc.
This safety element can occupy an internal position in the hoist as an independent unit, as was pointed out, by including the fixing or suspension element for the appliance in the said unit. In the same way, it can form part of a unit that occupies the exterior of the hoist.
In exactly the same way as in the case of the entryways for the chain into the hoist, the detectors can be microswitches, proximity detectors or any other kind of known elements that perform the same function.
The third safety element, an object of this invention, refers to the bag for gathering or collecting the chain and to the special design of some protuberances on the hoist casing for fixing the said bag and as a slide guide for the chain as it travels from the bag to the hoist and vice versa, as well as its seating or support on the side face of the casing, which is specially designed so that it can be used not only with the hoist in the normal working position, with the fixing element above, but also in the inverted working position, with the fixing element below.
This bag has a particular shape based on a hollow body with an approximately trapezoid plan view and side elevation, which, at its open upper end, is provided with projections or lugs provided with transverse drill holes, through which the bag is connected to the protuberances situated at the ends of the hoist casings.
The above-mentioned protuberances on the hoist casing are situated at the ends closest on the casing in relation to the area of the intake and output guides for the chain and, in the same way, they have transverse drill holes, so that by situating the protuberances or lugs on the bag and those on the casing in alignment with each other, a pin or bolt can be inserted and allows the bag to turn in relation to the said casings.
In the normal working position of the hoist, the hook or other fixing element is at the top and the chain guides are at the bottom, and the bag is situated with its side face, which is open, against the lower side of the frame or casing, so that the chain contained in the bag remains housed in the bag. In this position, the front outer face of the bag is in alignment with the side face of the hoist.
The other front outer face of the bag, on the side of the overhanging chain from which the hook is suspended, is provided with a curved concave hollow or cavity, through which the hook can travel when the bag is assembled.
When the hoist is in the inverted working position, the bag turns on the protuberances on the casing, and the front outer face moves to occupy a position in which it is supported against the side of the hoist.
In combination with the bag and the operation in the inverted working position, the protuberances situated on the hoist casing must be pointed out, with their outwardly convex rounded shape, which permit and facilitate the passage of the chain from the hoist to the bag and vice versa.
The hoist is composed of a first body or casing, which receives the electric drive motor on one of its sides, with the motor being secured to the casing by known means. On the same side and in a suitable housing, the permanent guiding unit is also received. This first component is provided with suitable holes that allow the motor outlet shaft and the gear reducer outlet shaft, which has to receive the star wheel of the permanent guiding unit, to pass through.
In the same way, the unit made up of the gear reducer and the clutch or torque limiter is received by the face of the opposite side of the said first body or casing, with this latter unit being seated or housed between the said face and the interior of a closing cover.
The shaft outlet of this gear reducer is received by the star wheel, surrounded by the permanent guiding unit, housed in the first body or casing, jutting out from the said unit in order to be housed in a second body or casing, which is fitted to the first body, forming an downwardly open cavity in order to allow the chain to enter and leave. The interior of these bodies or casings is provided with a neck on which a bearing is received and where the ends of the gear reducer shaft outlet are supported. Outside this second component is situated the whole of the assembly of electrical components to control the hoist, with the said exterior being closed by a lid which covers the said electrical components and the end of the electric motor on the side near the fan.
The points stated, and others relating to the invention, will be understood in a greater degree of detail by referring to the attached sheets of drawings, in which the following, in a non-restrictive way, are shown:

Figure 1 represents the hoist, in accordance with the invention, in the normal working position.
Figure 2 shows the same hoist, in the inverted working position.
Figure 3 represents a longitudinal cross-sectional view of the hoist.
Figure 4 represents the hoist and the arrangement of the incorporated integral safety items, which are objects of this invention: a permanent chain guide, detector guides for twisting or knotting, overload detector system, protuberances on the hoist casings and the bag to gather the chain.
We can also observe the irregular positioning of the chain links in the bag, which might cause problems when the load is being lowered.
Figure 5 represents the hoist and the arrangement of the incorporated integral safety items, which are objects of this invention, and the irregular positioning of the chain links on the sheave, which might cause problems when the load is being raised.
Figures 6 and 7 refer to two views of the permanent guiding unit provided with the safety device, in accordance with the invention.
Figures 8 and 9 show two views of the bag for collecting or gathering the chain, in accordance with the invention.
Figure 10 represents a rear view of the hoist, which allows the relationship between the bag for the chain and the protuberances on the casings of the hoist to be appreciated, in accordance with the invention.
Figures 11 and 12 represent details of the protuberances on each of the hoist casings, in accordance with the invention.

Looking now at Figure 1, it is possible to observe the hoist (1) with the hook or other fixing element (2) and the bag (3) for gathering the chain, as well as the electric cable (5) with its fast connector (4) to the electrical components of the machine, the chain (6) and the hook for hanging loads (7).
This position of the hoist (1) can be seen inverted in Figure 2, where the appliance is shown with the same elements, with the bag (3) turned on the protuberances (8) of the casings into this new position. It can also be observed, as will be explained more fully later, how the chain (6) slides over the curved convex exterior of the protuberance (8) in order to facilitate the passage of the chain from the hoist to the bag and vice versa.
In Figure 3, the existence of the hoist casings (17, 18) can be seen. The first of these (17) takes in the motor (9) and allows the outlet of the motor shaft (11) to pass through. In the same way, it receives the bearings corresponding to the gear reducer gear train (13, 14), and has another opening to allow the shaft outlet (15) of the said gear reducer to pass through.
This gear reducer, together with the clutch or torque limiter (12), is held inside the cover (20), while the shaft outlet (15) juts out through the opposite portion of this first casing (17) in order to receive the star wheel (16) and become housed in the second casing (18) of the hoist.
On the exterior of this latter part, we can see the assembly of electrical components (19) of the hoist, as well as the cover (20) that covers these said components, and the end of the motor (9) on the side near the fan (10).
The permanent guide (21) that surrounds the star wheel (16) becomes housed in a chamber between both casings, as can be observed, with this chamber being open at the bottom to allow the chain to enter and leave, during raising and lowering operations, although this opening is not illustrated in this figure.
According to Figure 4, which shows a preferable solution, attached to the casing (17) is the permanent guiding unit. made up of the permanent guide (21), surrounding the star wheel (16), which in turn is clamped onto the shaft outlet (15) of the gear reducer. This guide is an independent unit which is all fitted to the shaft outlet (15) and then secured by bolts to the casing (17).
Its general trapezoid shape can be appreciated, with perforations (22) in its longer side and blind drill holes (22) of a smaller diameter in the bases or bottoms of the said perforations. A hollow or recess is established between the perforations, in which a base (26) that includes two microswitches (27) is situated.
In the lower part or bottom, we can appreciate the two movable guides (24) provided with two lugs that include the adjustable contacts (25) aligned with the microswitches. These guides (24) are provided with holes aligned with those in the permanent guide (21) so as to receive bolts (22').
This arrangement can be appreciated with greater clarity in Figures 6 and 7 as regards the situation of the holes (28) in the guides (24) and their correspondence with the holes (22) in the guide (21), in both cases situated around the entryways or slots (29) for the chain, with these entryways being cut in both the movable guides (24) and in the permanent guide (21).
Between the guides (21) and (24), springs (23) which are received in the said perforations (22) are housed, after which the bolts (22') are inserted until they reach the base of the blind drill holes (22).
The bolts or pusher buttons (25) remain a certain specific distance from the microswitches, and this distance can be varied in terms of the greater or lesser penetration of the bolts (22'). The two microswitches are electrically connected (30) to the electrical control unit (19) for the hoist.
The operation of this device is very simple if we observe the irregular or uneven positioning of the chain links inside the bag (Figure 4) and on the sheave (Figure 5).
When the hoist works in a descending movement, as shown in Figure 4, one of the links (41) in the chain which is being paid out from the bag (3) is inappropriately positioned and, thus, when it tries to enter into the guides (24) it can not do so, with which it forces the guide (24) and obliges it to move in such a way that it makes contact with the microswitch. This sends a signal to the central control unit (19) and the motor is stopped.
The same occurs in the case shown in Figure 5, in which the hoist is working with a double length of chain. If for any reason the sheave with the hook (7) has been upturned, which is a fairly common occurrence, as shown in (M), there are chain links (41) which are incorrectly positioned, which means that they can not pass through the slots or entryways in the guides and force them to alter their position, automatically cutting off the motor operation.
Taking advantage of this safety mechanism of the invention, stops or limits (42) can be situated on the chain, so that, without any additional costs, the working heights of the hoist can be limited when it is ascending and descending.
At the same time, in Figure 4 we can observe the overload detector system and safety mechanism against overloads arranged in relation to the hook or fixing element for the hoist. Thus, the shaft (31) of the hook (2) receives a nut (34), which holds a pack of disc springs (32) against the hoist casing. Between this unit and the nut (34) is situated the part (33), which has a circular portion that receives the shaft (31) and a diametrical L-shaped projection (36), on the end of which is fitted a microswitch (37), as well as a lug (35) diametrically opposed to the l-shaped projection (36), with this lug being fitted to one of the faces of the nut (34) so that the part (33) does not turn and keeps the shaft of the microswitch (37) parallel to the hook shaft (31).
The microswitch (37) is aligned with the end of the bolt (38), which can be made to penetrate to a greater or lesser degree in order to adjust the distance between the two. The microswitch (37) is connected to the electrical control unit (19), so that when it makes contact with the bolt (38), a signal is transmitted which causes the motor to stop.
The contact in question takes place when an overload occurs which is capable of overcoming the spring action of the disc springs (32).
When this happens, the hook unit with the part (33) and the microswitch are raised in relation to the casing of the hoist until contact is made with the end of the bolt (38). This bolt is connected with a nut (39) in order to adjust its greater or lesser insertion or penetration and to set the desired position. The cavity or recess in which this nut (39) is located is closed by a part (40) in the for m of a lid or cover, which acts as a seal.
According to Figures 8 and 9, we can appreciate the configuration of the bag (3) which holds the chain and is trapezoid in shape in both perspectives. The bag (3) is open at the top and the upper ends form lugs (43) which are provided with holes so that they can be secured to the protuberances (8, 8) on the two bodies or casings of the hoist.
As illustrated in Figure 9, one of the faces of the bag (3) and more specifically the face (44), is shaped based on a curved recess whose purpose is to allow the hook (7) to pass through in the position illustrated in Figure 1.
When the hoist is in the position shown in Figure 1, the bag (3) is arranged with the upper opening just below the outlets for the chain that comes from the permanent guiding unit, and when the hoist works in the inverted working position, as shown in Figure 2, the bag occupies the area adjacent to one side of the hoist, as the bag itself has turned on the protuberances (8) on the hoist casings.
It is in Figure 10, precisely, where the position shown in Figure 1 is represented as seen from the rear view, in which it is possible to appreciate how the protuberances (8, 8) on the two component parts of the casing of the hoist are clasped by and fixed to the corresponding lugs (43) on the bag, with the help of a pin or bolt, not numbered, and its corresponding suitable adjustment nuts.
Finally, in Figures 11 and 12, some details of the bodies or casings (17) and (18) of the hoist are shown, with the protuberances (8, 8) on each of the casings being appreciated, with their convex outer sides (46, 46), along which the chain slides when the hoist is operating in the inverted working position, as shown in Figure 2.
In these same Figures 11 and 12, we can observe how the position (47) indicates the situation for the motor, and the positions (45) in the two casings (17, 18), which are used for housing the gear reducer outlet shaft (16???), as can also be appreciated in Figure 3.
It must be stated, for the appropriate purposes, that a hoist produced in accordance with this invention might include all the details described in one single unit or only some of them, as required, obviously in terms of the demands and performance features of the hoist.
The safety device against overloading arranged on the shaft of the hook (2) can be arranged, preferably, in the position shown in Figure 4 in the interior of the hoist casing and also on its exterior, depending on the suitability of each case.
It is important to emphasize, once having described the nature and advantages of this invention, its non-restrictive character, inasmuch as changes in the shape, material or dimensions of its constituent parts will not in any way alter its essence, as long as they do not mean a substantial variation of the whole.

Claims

A hoist, which has an electric motor (8), a gear reducer (13, 14) provided with a clutch or torque limiter (12) closed by a lid or cover (20), two central bodies or casings (17, 18) that take in the shaft outlet (15) from the said gear reducer to the star wheel surrounded by a chain, with a guide that takes in the star wheel (16) and the chain (6) and is housed in the interior of the hoist casings, as well as an electrical control unit (19), an outer cover (20) and a hook or other fixing element (2), which is characterized by:
- two movable guides (24) secured in a floating manner on the hoist and provided with cross-shaped entryways or slots (29), through which the links in the chain pass when coming from the exterior towards the cross-shaped slots (29) in the guide (21), with the entryways or slots (29) being aligned with the slots (29) and the movable guides (24) being in parallel planes to those of the chain outlets in the guide (21) with damper or shock absorber items being arranged between both guides, aimed at keeping a distance or gap between them, in that one part of each one of the movable guides (24) is to be found at a certain distance from some detector devices secured to the hoist and connected to the electrical control unit, which cut off the current to the motor when they are activated by the portions of the movable guides due to the guides (24) being moved by the action of incorrectly aligned or positioned links in the chain,

- a safety device against overloads, incorporated into the shaft of the hook or fixing element (2), provided with a nut (34) that receives a part (33) above it that clasps the shaft and keeps a shock absorber unit against a fixed portion, in that the part (33) that surrounds the shaft (31) is provided with a diametrical L-shaped projection (36) on which a detector (37) is housed, positioned parallel to the shaft of the hook or fixing element, as well as another projection (35) diametrically aligned with the part that is fitted to one of the faces of the nut, in that the detector is aligned, in turn, with the with an adjustable bolt (38) arranged on the exterior of the previously-mentioned fixed portion,

- two protuberances (8, 8) on the casings (17, 18), at the ends close to the outlet area for the chain, which are provided with holes and aligned with each other, with outwardly convex rounded sides (46, 46) on the side of the chain outlet area, which guide and facilitate the passage of the chain in its travel from the hoist to the bag and vice versa, preventing blockages or jamming,

- a special bag (3) to collect or gather the chain, which is a hollow body, open at the top, with a trapezoid front and side shape, provided with a set of lugs (43) which are holed and aligned with each other and fit onto the exterior of the protuberances (8, 8) on the hoist casings through a shaft on which the bag turns or pivots, with one side of the bag also having a curved concave recess (44) to allow the chain hook to pass.
A hoist, in accordance with claim 1, characterized in that in a preferable solution, two equal movable guides (24) are arranged, situated over the areas of the cross-shaped entryways or slots for the chain, with the movable guides being provided with cross-shaped slots (29) aligned with those in the guides and each surrounded by four perforations (28), also aligned with those in the permanent guide (21) and of the same diameter, in that these perforations (28) have a longitudinal cross section in the form of a double "T", with springs also being arranged between the permanent guide (21) and these guides (24), housed in the perforations (22) in the said permanent guide (21) and in those in the guides (28), and the perforations (28) in the guides (24) receiving a set of bolts (22') that fix the movable guides to the permanent guide, and some side projections jutting out from the front faces of the guides (24) towards the central recess and prolongation of the guides in which a set of bolts or pusher buttons (25) are situated and remain a certain distance from the ends of the two microswitches (27) arranged in a part secured to the base (26) of the said central recess.
A hoist, in accordance with claim 1, characterized in that the movable guides (24) are arranged in a floating manner on the hoist casing.
A hoist, in accordance with claim 1, characterized in that the detectors are proximity detectors.
A hoist, in accordance with claim 1, characterized in that the detectors for the movable guides are situated on the hoist casing.
A hoist, in accordance with claim 1, characterized in that the detectors for the movable guides are situated on the chain guide.
A hoist, in accordance with claim 1. characterized in that the damper or shock absorber items are flexible rubber parts.
A hoist, in accordance with claim 1, characterized in that the damper or shock absorber items are Belleville discs.
A hoist, in accordance with claim 1, characterized in that the movable guides are provided with attached projections jutting out towards the detectors.
A hoist, in accordance with claim 1. characterized in that the safety device against overloads incorporated into the fixing element is housed in a unit independent of the hoist casing and is secured to it by any means whatsoever.