Claims:
I claim
1. A hoist apparatus comprising:
2. The apparatus of claim 1 wherein:
3. The apparatus of claim 2 wherein:
4. a strut portion,
5. a wheel journaled on said strut portion and engaging said track member,
6. a ring portion, and
7. a hub portion projecting from said ring and extending into said open end;
8. The apparatus of claim 2 wherein said nut means includes a ball raceway having an arcuate working portion extending along a portion of the periphery of said drum and a ball return portion forming with the working portion a closed loop, said raceway having a plurality of balls disposed therein which engage a portion of said helical groove means.
9. A hoist apparatus comprising:
10. A hoist apparatus comprising:
11. a strut portion,
12. means mounting said strut portion for movement along said track member,
13. a ring portion, and
14. a hub portion projecting from said ring; C. a drum having an open and journaled on said hub portion;
15. A hoist apparatus comprising:
16. a strut portion,
17. means mounting said strut portion for movement along said track member,
18. a ring portion, and
19. a hub portion projection from said ring;
Description:
BACKGROUND OF INVENTION
This invention relates to hoists of the type including a drum and a cable wound on the drum in helical fashion. More particularly, this invention relates to cable hoists of the level wind type, i.e., hoists which have provision to ensure that the cable is wound on the drum in even layers with each layer lying in a single cylindrical plane concentric with the central drum axis. Many level wind hoist designs have been proposed and/or commercially utilized. While most of these prior art level wind hoists have been satisfactory for their intended purpose, none have proven capable of providing reliable and durable operation at high load levels.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved hoist structure.
A more specific object is to provide a cable hoist of the level wind type having a combination of simplicity and high load capacity not found in any of the prior art level wind hoists.
According to an important feature of the invention, the hoist is provided with a rotary type motor and the output shaft of the hoist motor is drivingly connected to the cable drum to rotate the drum about its central axis; a helical groove is provided on the cable drum centered on the central drum axis and a nut member, rigid with the hoist frame, engages the helical groove so that, as the drum is positively rotated by the hoist motor, the nut member coacts with the helical groove to move the drum axially along the frame of the hoist.
According to another important feature of the invention, the helical groove is provided on the exterior cylindrical surface of the drum and the cable is wound in a portion of this helical groove; the nut member engages a vacant portion of the helical drum groove so that the pay-out location of the cable remains fixed with respect to the hoist frame as the rotating drum moves axially relative to the hoist frame in response to threading of the drum past the nut member.
In the preferred embodiment of the invention, the cable is wound in the helical groove from one end of the groove toward the other end of the groove and the nut member comprises a ball nut which is located on the frame adjacent the fixed pay-out location of the cable and on the side of the pay-out location adjacent the vacant end of the groove so that the ball nut engages successive portions of the groove as these portions are successively vacated by the unwinding cable.
These and other objects and features of the invention will be apparent from the detailed description of the preferred embodiment and from the drawings .
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a perspective view of a hoist according to the invention;
FIG. 2 is a longitudinal cross-sectional view of the invention hoist;
FIG. 3 is a view on an enlarged scale of the hoist structure within the detail circle 3 in FIG. 2; and
FIGS. 4 and 5 are end views of the invention hoist locking in the direction of the arrows 4 and 5, respectively, in FIG. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to FIG. 1, the invention hoist, broadly considered, comprises a frame structure 10, a carriage 12 adapted to ride along frame structure 10, a drum 14 journalled on carriage 12, a motor 15 on carriage 12 for drivingly rotating drum 14, a cable 16 wound on drum 14, and a nut mechanism 18 engaging drum 14.
Frame structure 10 comprises a pair of horizontally arranged confronting channel members 20, 22 defining a pair of spaced horizontal track surfaces 24, 26. Channel members 20,22 are suitably suspended in an overhead position, e.g., over a factory work station where hoisting operations are required.
Carriage 12, as seen in FIGS. 1 and 2, is a two-part bolted together structure including a truck member 28 and a journal member 30. Truck member 28 includes a ring portion 28a, strut portions 28b extending integrally and generally tangentially downwardly from either side of ring portion 28a, feet portions 28c formed integrally at the lower ends of strut portions 28b, and wheel pairs 28d journalled in tandem fashion on feet 28c and guiding on track surfaces 24,26. Journal member 30 includes a hub portion 30a, an outwardly directed flange portion 30b on one end of hub portion 30a, and an inwardly directed flange portion 30c on the other end of hub portion 30a. Bolts 32 passing through aligned apertures in flange portion 30b and ring portion 28a coact with nuts 34 to secure members 28 and 30 rigidly together.
Drum 14 has a laminated construction and includes a central, structural, cylinder 36, formed for example of cast aluminum, and an outer cylindrical sleeve 38, formed for example of molded polyurethane. Polyurethane sleeve 38 butts against a flange 36a formed on one end of aluminum cylinder 36 and is preferably bonded to the outer surface of cylinder 36. Sleeve 38 defines a single continuous helical groove 40 on its outer periphery extending from end to end of the sleeve. As best seen in FIG. 3, the bottom of groove 40, in cross section, is formed as a circular arc to provide minimum bearing stress and the tops of the grooves, i.e., the ridges between the grooves, are radiused as shown to facilitate guidance of the winding cable into the successive convolutions of the groove. For example, the successive groove convolutions may be spaced at "pitched" 1.25 inches apart and the groove bottom may be given a radius of 0.52 inches.
Drum 14 is hollow and is journalled on hub portion 30a by a pair of ball bearing 42 and 44. Ball bearing 42 has its inner race 42a pressed onto hub portion 30a and its outer race 42b fitted in an annular groove 36b formed in flange 36a of the aluminum cylinder. Ball bearing 44 has its inner race 44a pressed onto hub portion 30a at a location spaced from inner face 42a, and has its outer race fitted into aluminum cylinder 36 adjacent a thickened annular central cylinder portion 36c.
Motor 15 may take any of several forms. It may comprise an electric motor, or a hydraulic motor, or, as in the disclosed embodiment, an air motor supplied with pressurized air from a suitable source through a hose 46. Air motor 15 includes a central output shaft 48 driving a suitable speed reduction mechanism 49 whose output drive member comprises an internally toothed ring gear 50 drivingly coupled to aluminum cylinder 36 by a plurality of screw bolts 51 in flange 30c; actuation of motor 15 thus serves to positively rotate drum 14 at an angular speed substantially reduced from that of motor output shaft 48. Motor 15 and speed reduction mechanism 49 are positioned on hub portion 30a within the hollow end of drum 14 by a plurality of bolts 52 passing through suitable aperatures in flange portion 30c. Details of the structure and operation of an air motor and speed reduction mechanism suitable for use as the drum rotating mechanism of the invention hoist are disclosed in copending U.S. Pat. application Ser. No. 74,463 filed Sept. 22, 1970 and assigned to the assignee of this application. A control box, seen schematically at 53, is secured to reduction mechanism 49 and power is supplied to box 53 by a suitable electric cord 54.
Cable 16 is wound in helical fashion in groove 40 defined in polyurethane sleeve 38. Cable 16 is wound in groove 40 from the end of the groove adjacent carriage 12 toward the other end of the sleeve and pays out from drum 14 at a location adjacent but immediately preceding nut mechanism 18. Cable 16 may be utilized in a single rope system in which the cable is fastened directly to the load engaging hook 55 or, as shown, it may be used in a single rope reeved system in which the cable passes through a pulley 56 on hook 55 and is fastened at its free end to channel member 22.
Nut mechanism 18, as best seen in FIGS. 2, 3, and 5, includes a partial ball nut structure 57 and a yoke structure 58. Ball nut structure 57 includes a cast aluminum support block 59, ball guide members 60, and balls 62. Aluminum block 59 is rigidly secured to a transverse angle member 64 as by bolts 66 and angle member 64 is in turn rigidly secured to frame channel members 20, 22 as by bolts 68. The upper face of block 59 is saddle shaped to match the curvature of polyurethane sleeve 38 and is cast with three side-by-side integral grooves 70.
Grooves 70 are spaced apart by a distance to match the pitch of helical groove 40, and the cross-sectional configuration of grooves 70 matches the cross-sectional configuration of groove 40. Grooves 70 are not normal to the central drum axis but rather are askew with respect to that axis by an amount to approximate the skew of helix 40. Block 59 is also provided with three transverse bores 72, underlying and corresponding to the three grooves 70.
Ball guide members 60 are formed of stamped sheet metal. Each member 60 is generally corrugated in cross section to define three side-by-side arcuate grooves. Each member 60 is secured at its lower end to aluminum block 59 by a screw 74 and extends upwardly in arcuate form to define three ball raceways with the adjacent arcuate end surface 59a of block 59. It will be seen that a groove 70, corresponding bore 72, and a corresponding groove or corrugation in each of the left and right guide members 60 coact to define a closed raceway for balls 62 and that the grooves, bores and guides taken in toto define three side-by-side entirely independent ball raceways which coact with three adjacent convolutions of helical groove 40 to provide a partial ball nut which functions to support the drum as well as thread the drum axially in response to rotation of the drum.
Yoke structure 58 comprises a channel member 75 which is welded at its lower ends to opposite faces of aluminum block 59 and curves intermediate its ends in arcuate form over drum 14 to provide journal supports for a pair of retaining wheels 76. Wheels 76 have the same skew as groove 40 and guide in groove 40 to preclude vertical displacement of drum 14 relative to ball nut 56.
OPERATION OF PREFERRED EMBODIMENT
With the carriage and drum in the extreme leftward position of FIG. 2, the three ball races of ball nut 57 engage the last three complete convolutions of helical groove 40 and load hook 55 is in its raised position. When it is desired to lower load hook 55 to pick up a load, pressure air is supplied to motor 15 and the motor is energized in a sense to rotate drum 14 clockwise as viewed in FIG. 5. As drum 14 rotates clockwise, cable 16 unwinds from the drum and the drum is moved axially rightwardly, as viewed in FIG. 2, by the threading engagement of ball nut 57 with groove 40. Since the pay-out location of the cable on the drum is moving leftwardly (FIG. 2) along the drum at the same rate that the drum is threading rightwardly relative to the hoist frame through the ball nut, the pay-out location of the cable relative to the hoist frame remains fixed. When the load has been engaged and it is desired to raise the cable, motor 15 is energized in an opposite sense and drum 14 is rotated counterclockwise as viewed in FIG. 5 to wind the cable back on the drum. The threading engagement of the ball nut in the helical cable groove moves the drum leftward (FIG. 2) at the same rate that the pay-in location is moving rightward along the drum so that the pay-in location remains fixed.
The invention apparatus will be seen to provide a cable type hoist structure of extremely simple and durable design and having an inherently high load capacity.
Although a preferred embodiment of the invention has been illustrated and described in detail with reference to the accompanying drawing, it will be understood that various changes and modifications may be made in the disclosed embodiment without departing from the scope or spirit of the invention.