Abstract:
An end surface gear-type overload protection device for manually operated hoists that utilizes a disc-shaped spring to control tension such that when the gears are in a leftward rotation and engagement, operation continues normally. However, during rightward rotation and the disabling thereof is instructed due to the clutch-type ratchet overload protection device, when in the “overload prevention” operations mode, if the set load of the disc-shaped spring is exceeded, the clutch-type gear wheel after sensing such allows the operating lever to spin in neutral and thereby discontinue operation. Additionally, it is possible to simply adjust the operating configuration to the “non-overload prevention” operations mode to conduct operation under overload conditions.

Description:
BACKGROUND OF THE INVENTION 
   1) Field of the Invention 
   The invention herein relates to mechanical rotation safety protection mechanisms, specifically an end surface gear-type overload protection device for manually operated hoists. 
   2) Description of the Prior Art 
   Conventional manually operated hoist structures are categorized into two types: hand crank type or hand chain type, wherein the “hand crank type” hoist, as shown in  FIG. 13 , is comprised of a load pulley wheel  2  ensconced along with a bearing device between a pair of side plates  1  as well as an operating drive component  3  disposed at the outer lateral extent of the side plates  1  that drives a transmission shaft  4  accompanied by a gear reduction mechanism  5  at its axial lateral extent, said drive component  3  consisting of a hand crank arm  3   a  having a single-direction drive ratchet wheel  3   b , a pawl  3   c , and a pawl spring  3   d  such that the rapid operation of the hand crank arm  3   a  turns the drive shaft  4  which pulls over said load pulley wheel  2  a chain  6  connected to a hoisting hook  6   a  coupled to a heavy object; the “hand pull type” hoist, as shown in  FIG. 14 , generally consists of, in common with the hand crank type structure, side plates  1 , a load pulley wheel  2 , a transmission shaft  4 , a gear reduction mechanism  5 , a chain  6  connected to a hoisting hook  6   a , and other necessary drive components, the difference is that the power input section drive component  7  is instead a hand pull chain  7   a  and at its lateral axial aspect has a direction alternating ratchet wheel  8  and a pawl  8   a  which replaces the drive component  3  of said hand crank type structure, the hand pull type variant utilizing the hand pull wheel  7  over which is diametrically disposed a hand pull chain  7   b  to draw and thereby operate, at the other end of the transmission shaft  4 , a load pulley wheel  2  and its chain  6  connected to a hoisting hook  6   a  coupled to a heavy object; since the hand crank type and the hand pull type structures are uncomplicated, portable, and convenient, they are widely used for loading cargo, unloading cargo, and strapping cargo. As such, in keeping with their operating characteristics, they are often utilized in an overloaded state and there is no limiting overload setting which, especially when lifting and strapping loads, tends to concentrate hoisting load stress at certain points, the hoisting hook  6   a  easily subjecting the chain  6 , brake, and other components of the hoist to excessive wear, while also easily damaging goods and causing industrial accidents wherein operating personnel suffer injury. 
   SUMMARY OF THE INVENTION 
   The primary objective of the invention herein is to provide an end surface gear-type overload protection device for manually operated hoists, providing a hand crank type hoist or a hand pull type hoist that, in view of overload incurred wear or accidents attributed to such hoists in the past, integrates a safety device that senses a preset overload weight and, furthermore, automatically halts operation to thereby prevent hoisting rig damage and operating personnel industrial injury and accidents. 
   The unique features of the structure herein includes the utilization of a disc-shaped spring to control tension such that during leftward gear rotation and enmeshment normal operation continues, but during rightward rotation when instructions cannot be executed by the clutch-type gear installed to prevent overload and the invention is in the “overload prevention” operating mode, if the set load of the disc-shaped spring is exceeded, the clutch-type gear after sensing such allows the operating shaft to spin in neutral continuously. Additionally, said structure can be simply adjusted to a “non-overload prevention” operating mode to thereby permit operation under overload conditions. 
   As such, the end surface gear-type overload protection device for manually operated hoists of the invention herein is a structure capable of utilization in either a hand crank type hoist or a hand pull type hoist to provide such manually operated hoists a practical means of overload control. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded drawing of the first most preferred embodiment of the invention herein. 
       FIG. 2  is a cross-sectional drawing of  FIG. 1 , showing a partial aspect in magnified view. 
       FIG. 3  is an orthographic drawing of the drive component, umbrella type gear ring of the invention herein. 
       FIG. 4  is an orthographic drawing of the drive component, umbrella type gear ring of the invention herein. 
       FIG. 5  is an orthographic drawing of the drive component sleeve, umbrella type teeth section of the invention herein. 
       FIG. 6  is an orthographic drawing of the drive sleeve, umbrella type teeth section of the invention herein. 
       FIG. 7  is an isometric drawing of the locating ring and the adjustment nut of the invention herein. 
       FIG. 8  is an isometric drawing of the assembled locating ring and adjustment nut of the invention herein. 
       FIG. 9  is an orthographic drawing of the drive component and drive sleeve when engaged in forward rotation. 
       FIG. 10  is an orthographic drawing of the drive component and drive sleeve when engaged in rearward rotation. 
       FIG. 11  is an exploded drawing of the second most preferred embodiment of the invention herein. 
       FIG. 12  is a cross-sectional drawing of the second most preferred embodiment of the invention herein, showing a partial aspect in magnified view. 
       FIG. 13  is an exploded drawing of a conventional manual crank type hoist structure. 
       FIG. 14  is an exploded drawing of a conventional manual pull type hoist structure. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   To elaborate the “manual crank type” hoist structure of the present invention, as indicated in  FIG. 1  and  FIG. 2 , the invention herein is comprised of two side plates  1 , a load pulley wheel  2 , a drive component  3 , a transmission shaft  4 , and a gear reduction mechanism  5 , with a hand crank arm  3   a  that is turned rapidly to impel the transmission shaft  4 , thereby causing the load pulley wheel  2 , on which is mounted a chain  6 , to draw a connected hoisting hook  6   a  coupled to a heavy object; since this aspect of the arrangement is identical with that utilized conventionally, it shall not be further described; the original design feature of the invention herein is that the drive component  3  ratchet wheel  3   b , at its lateral area of rotation, includes an umbrella type gear ring  10 , an elastic component  20 , a drive sleeve  30 , an adjustment nut  40 , an equalizing washer  50 , and a locating ring  60  in a insertional spatial arrangement, the unique features of which include: 
   Referring to  FIG. 1  and  FIG. 2 , the umbrella type gear ring  10  and the ratchet wheel  3   b  end surface constituted into a single structural entity, the end surface consisting of slanted facets  11  postured at a predetermined angle and, as indicated in  FIG. 3  and  FIG. 4 , the optimal angle α of each slanted facet  11  is 20 degrees, while situated perpendicularly at the terminus of each slanted facet  11  is a land section  12 , and reticulated axially at the rear end of the drive component  3  ratchet wheel  3   b  is a recess  13 . 
   Referring to  FIG. 1  and  FIG. 2 , the elastic component  20  is seated in the recess  13  of the ratchet wheel  3   b  and is optimally a disc-shaped spring. 
   Referring to  FIG. 1  and  FIG. 2 , the drive sleeve  30  is placed axially onto the transmission shaft  4 , one end consists of a relatively large diameter holding flange  31  with the other end consisting of relatively narrow diameter hollow neck  32  and, as indicated in  FIG. 5  and  FIG. 6 , the holding flange  31  has an umbrella type teeth section  311  consisting of inclined angle troughs and peaks that enmesh the umbrella type gear ring  10 , the slanted facets  311 A of which are each postured at a predetermined angle β, the optimum predetermined angle β of each slanted facet being 20 degrees, and situated perpendicularly at the terminus of each slanted facet  311 A is a land section  311 B; the hollow neck  32  is inserted axially through the umbrella type gear ring  10  and the ratchet wheel  3   b  and, furthermore, external threads  321  are died onto its extremity. 
   Referring to  FIG. 2  and  FIG. 7 , the adjustment nut  40  is a rectilinear body and, furthermore, internal threads  41  are tapped through its center for fastening onto the external threads  321  at the extremity of the drive sleeve  30 ; a bottoming section  42  is machined flat along the front extremity and a quantity of notches  43  are disposed along the outer circumference; and two anchoring holes  44  are drilled diametrically in the end surface to position a shaft collar bearing  45  (see  FIG. 1 ) in the bearing hole  3   e  of the hand crank arm  3   a.    
   Referring to  FIG. 1  and  FIG. 2 , the equalizing washer  50  is an annular rigid body that is disposed pivotally at the inner sides of the elastic component  20  and the adjustment nut  40  such that when the adjustment screw  40  is tightened, it provides equalized pressure axially against the elastic component  20 . 
   Referring to  FIG. 1  and  FIG. 2 , the locating ring  60  is an annular washer that is seated pivotally between the sides of adjustment screw  40  and the equalizing washer  50  and, as indicated in  FIG. 7  and  FIG. 8 , has a bottoming flat surface  61  that corresponds to the bottoming section  42  along the front end of the adjustment screw  40  and, furthermore, six tabs  62  protruding towards the notches  43  to provide for the radial fixing by insertion of the adjustment screw  40  position. 
   Based on said assembly, the operation and utilization of the end section gear type overload protection device for manually operated hoists of the invention herein is as follows: Referring to  FIG. 2 , the adjustment screw  40  is fastened into the external threads  321  at the extremity of the drive sleeve  30  to axially clamp together the drive component  3  ratchet wheel  3   b , the elastic component  20 , the drive sleeve  30 , the equalizing washer  50 , and the locating ring  60 , utilizing the adjustment screw  40  to produce axial pressure against the drive component  3  and, via the equalizing washer  50 , apply balanced pressure against the elastic component  20  such that changes in its shape result in axial thrust which provides the required load torsion. 
   At the same time, the skewered and clamped drive component  3  ratchet wheel  3   b  at the end surface of the umbrella type gear ring  10  enmeshes the drive sleeve  30  umbrella type teeth section  311 , as shown in  FIG. 9  and  FIG. 10 , increasing the elastic component  20  rebound force, and thereby increasing the friction laterally exerted between the umbrella type gear ring  10  and the umbrella type teeth section  311 , such that the drive component  3  ratchet wheel  3   b  requires the transfer of greater torsion before slippage occurs and conversely the transfer of less torsion to readily allow slippage; when a load exceeds the set torsion of the load pulley wheel  2  at the emergent tip of the transmission shaft  4 , the hand crank arm  3   a  turning the ratchet wheel  3   b  slips to protect against inputted transmission overload. 
   As a result, when no overload occurs during the transmission process, the ratchet wheel  3   b , the drive sleeve  30 , the equalizing washer  50 , and the locating ring  60  remain clamped together and, as such, given the alternating directional operation of the hand crank arm  3   a  ratchet wheel  3   b  with a pawl  3   c , as indicated in  FIG. 9 , the two land sections  311 B and  12  engage perpendicularly to achieve forward rotation or, as indicated in  FIG. 10 , the umbrella type gear ring  10  and the umbrella type teeth section  311  slanted facets  311 A and  11  engage to achieve reverse rotation operation, and with the rapid up and down movement of the hand crank arm  3   a , the transmission shaft  4  pulls the chain  6  mounted over the load pulley wheel  2  and thereby raises the hoisting hook  6   a  coupled to a heavy object. 
   When an overload occurs during the transmission process, the umbrella type gear ring  10  and the umbrella type teeth section  311  slanted facets  311 A and  11  that were originally pushed and squeezed against each other are then impelled laterally to disengage the land sections  311 B and  12 , following which they fall into another engagement with the slanted facets  311 A and  11  and, as a result, umbrella type gear ring  10  and the umbrella type teeth section  311  slip apart and spin in neutral, manifesting a metallic frictional sound that informs the operator of the overload, thereby ensuring work safety. 
   Additionally, the hand crank arm  3   a  and the transmission shaft  4  of the invention herein, at their lateral area of rotation, includes an umbrella type gear ring  10 , an elastic component  20 , a drive sleeve  30 , an adjustment nut  40 , an equalizing washer  50 , and a locating ring  60  in a insertional spatial arrangement, and although utilized to provide for “overload prevention” operations mode with a procedure for setting hoist load limits, the present invention is easily adjusted into a “non-overload prevention” operations mode, the procedure only requiring the removal of the locating ring  60  tabs  62  that were originally inserted into said notches  43 , which thereby releases the fixed state of the adjustment nut  40  to accommodate specific working requirements and, as such, tasks can be performed under overload conditions if desired because the adjustment procedure is very simple. 
   Referring to  FIG. 11  and  FIG. 12 , to elaborate the invention herein utilizing a “manual pull type” hoist, the present invention is comprised of two side plates  1 , a load pulley wheel  2 , a drive component  7 , a transmission shaft  4 , and a gear reduction mechanism  5 , via the drive component  7  hand chain wheel  7   a  and a hand chain  7   b  that rotate and are driven on the transmission shaft  4 , wherein a chain  6  mounted over the load pulley wheel  2  draws a connected hoisting hook  6   a  coupled to a heavy object, and since these aspects of the arrangement are identical with that of conventional manual pull type hoists, they shall not be further described; however, the unique features of this embodiment are the same as those disclosed of the manual crank type hoist and includes an umbrella type gear ring  10 , an elastic component  20 , a drive sleeve  30 , an adjustment nut  40 , an equalizing washer  50 , and a locating ring  60  in an insertional spatial arrangement that are respectively disposed at the axial end surfaces at the two sides of the drive component  7  hand chain wheel  7   a.    
   Referring to  FIG. 12 , screws or rivets (not shown in the drawings) fasten the umbrella type gear ring  10  and the drive component  7  hand chain wheel  7   a  axially at the end surfaces to conjoin them into a single entity, and utilizing the drive sleeve  30  axially, the hollow neck  32  is inserted lengthwise through the hand chain wheel  7   a  and the umbrella type gear ring  10  and, furthermore, the elastic component  20 , the equalizing washer  50 , and the locating ring  60  are respectively and pivotally conjoined to the other lateral end of the hand chain wheel  7   a  and, finally, the adjustment nut  40  is similarly fastened tight onto the external threads  321  along the end of the drive sleeve  30  such that the drive component  7  hand chain wheel  7   a , the elastic component  20 , the drive sleeve  30 , the equalizing washer  50 , and the locating ring  60  are axially conjoined into a single entity; utilizing the adjustment nut  40  tightness to produce pressure against the drive component  7  and axially towards the hand chain wheel  7   a , the equalizing washer  50  transfers balanced force against the elastic component  20 , its changes in shape resulting in axial thrust that produces the required load torsion; since the structural components are insertionally conjoined such that the umbrella type gear ring  10  at the end surface of the drive component  7  hand chain wheel  7   a  is against the drive sleeve  30  umbrella type teeth section  311 , as shown in  FIG. 12 , increasing the elastic component  20  force increases the lateral contact friction between the umbrella type gear ring  10  and the umbrella type teeth section  311 , the hand chain wheel  7   a  required to transfer greater rotational torque before the onset of slippage, with the converse action requiring the transfer of less rotational torque before slippage; when the load pulley  2  at the emergent end of the transmission shaft  4  is subjected to a load that exceeds the set rotational torque, then the hand chain wheel  7   a  pulled and controlled by the hand chain wheel  7   b  slips to protect the inputted transfer from overload. 
   To continue, when no overload occurs during the transmission process, as indicated in  FIG. 9 , the land sections  311 B and  12  engage perpendicularly to achieve forward rotation or, as indicated in  FIG. 10 , the umbrella type gear ring  10  and the umbrella type teeth section  311  two slanted facets  311 A and  11  engage to achieve reverse operation, and the hand chain  7   b  pulls the transmission shaft  4  to draw a chain  6  mounted over the load pulley wheel  2  that is connected to the hoisting hook  6   a  coupled to a heavy object. 
   When an overload occurs during the transmission process, likewise, the umbrella type gear ring  10  and the umbrella type teeth section  311  two slanted facets  311 A and  1 I that were originally pushed and squeezed against each other are then impelled laterally to disengage the land sections  311 B and  12 , following which they fall into another engagement with the slanted facets  311 A and  11  and, as a result, the umbrella type gear ring  10  and the umbrella type teeth section  311  slip apart and spin in neutral, thereafter manifesting a metallic frictional sound to inform the operator of the overload to ensure work safety.