US2680004A

US2680004A - Hoist

Info

Publication number: US2680004A
Application number: US197193A
Authority: US
Inventors: Herker Kurt
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-12-03
Filing date: 1950-11-24
Publication date: 1954-06-01
Anticipated expiration: 1971-06-01

Description

June 1, 1954 K. HERKER 2,680,004

I HOIST Filed Nov. 24, 1950 2 She-cs-Sheet 1 lnven for- Hera a r June 1, 1954 HOIST Filed NOV. 24, 1950 2 Sheets-Sheet 2 fig- 3 /22 ll? I23 L/ff/rzg Spee E/eva fion I In venfor K rt/femur K. HERKER I 2,680,004 V Patented June 1, 1954 UNITED STATES ATENT OFFICE Claims priority, application Germany December 3, 1949 2 Claims.

The present invention relates to a hoist, more particularly to a hoist such as used in workshops and the like for lifting or lowering comparatively small loads at different speeds. Prior to the present invention hoists of this type were either equipped with a variable speed motor or with a main lifting motor and a supplemental load adjusting motor, the latter being adapted to be optionally connected with the lifting drum in lieu of the main lifting motor. In a prior hoist of that kind the load adjusting motor was equipped with an axially shiftable armature adapted by its shifting motion to be connected with the lifting drum. The speed of operation of the main lifting motor was capable of reduction by the insertion of electrical resistances. Hoists of that kind were complicated and expensive.

It is the main object of the present invention to provide a hoist which is capable of lifting and lowering the load at diiferent speeds, but is much simpler in design and more reliable in operation and less expensive to manufacture than the prior variable speed hoists.

It is a further object of the present invention to reduce the power required for operation of the hoist, thus enabling a smaller electrical motor to be used than was possible in prior designs.

Further objects of the present invention will appear from the description of two preferred embodiments thereof which are illustrated in the accompanying drawings, whereas the features of novelty will be pointed out in the claims.

Fig. 1 is an elevation of the novel hoist;

Fig. 2 is the section taken along line 22 of Fig. 1;

Fig. 3 illustrates a plan view of a motor-driven hoist, partly shown in section;

Fig. 4 is a chart diagrammatically illustrating the lifting speed of the load in dependence on the elevation thereof.

The supporting structure of the hoist shown in Figs. 1 and 2 is formed by a casing l integral with upper transverse beam l2 having lugs II for attachment thereof to the ceiling of a workshop or to a suitable carriage running on rails beneath such ceiling. The casing [0 has suitable bearings I 3 in which the shaft of a worm M is J'ournalled. This shaft is connected with the motor shaft of an electric motor I5 suitably attached to the casing l0. Beneath the worm I4 and extending at a distance therefrom transversely thereto, there is journalled a shaft [6 in anti-friction bearings I1, and in a second bearing 18 carried by a movable end plate l9 suitably attached to the gear casing I 0. Between the. bearings l! and [8 a worm gear 20 is splined on the shaft is and engages the worm M. In this manner, the electric motor l5 may operate the shaft 55 at a reduced speed. On the right-hand end 2!, viewed in Fig. 2, a lifting drum is attached by a key 23. This drum comprises an inner cylindrical section 24 of a comparatively large diameter, an outer cylindrical section 25 of a comparatively small diameter and a transitional more or less conical section 26 connecting the two

sections

24 and 25. A single peripheral groove 23 shaped to accommodate a lifting rope fl is provided on the outside of the drum 22 extending over the three

sections

24, 26 and 25. On the conical section 26 the groove 23 may extend in a spiral fashion through V to 2 convolutions or may extend more or less straight tangentially to the drum section 25. While the outer end of the rope extends downwardly, as shown at 21, carrying a hook or the like for attachment of the load, the other end of the rope is firmly fixed to the drum.

To the left-hand end of shaft [6 there is detachably connected for common rotation therewith a sleeve 29. For the purpose of such attachment the sleeve may have a transverse pin 30 engaging a diametral slot provided in the end face of the shaft it. A spherical head 34 of a stud 32 extending into the sleeve 29 is axially attached to a cap 33 which is suitably fixed to the end plate H! of the casing. A spiral leaf spring 35 surrounds the sleeve 29 inside the cap 33 and has its inner end fixed to the sleeve 29 and its outer end fixed to the cap 33 which thus constitutes a spring barrel which may be filled with oil to reduce the friction of the convolutions of the spring upon each other. The cap 33 is held against rotary displacement on the end plate H) by suitable means not shown permitting to attach the cap in different angular positions, whereby the cap may be detached, turned and re-attached again for the purpose of adjusting the bias of the spring. The drum is surrounded by a suitable sheet metal casing 35 attached to the gear casing H) by bolts 36 and its lower left quadrant, viewed in Fig. 1, is cut. out for the purpose of permitting passage of the rope 2'; to and from the drum. It will appear from Fig. 2 that the cross-section of the groove 28 is so tapered as to exert a clamping effect. on the rope 21, so that its depth is about two to three times the diameter of the rope.

A switch provided inside of a switch casing- 3'! mountedon the bottom of the casing of motor i is so operable as to stop the motor when the rope has either been fully unwound or fully wound up. For this purpose a bent arm 38 (Fig. 1) is suitably journalled for rotation about a vertical axis, the lower end of such arm 38 forming a loop 39 embracing the downwardly extending section of the rope 27. The loop 39 is so dimensioned as to be engaged by the rope 21 when the same approaches either the left or the right end of the groove. The arm 38 is connected by suitable links 40 to the switch provided in casing 31. Preferably, the motor i5 is a type and of a size permitting the motor to be supplied with energy from the electrical light installation. The spiral spring 34 is so wound as to increase its bias by a rotation of the drum in a direction lowering the rope 21.

The embodiment illustrated in Figs. 3 and 4 is similar and differs from that shown in Fig. 1 primarily by the absence of the spiral spring 34. Similar elements of the hoist shown in Fig. 3 are designated by reference numerals obtained by adding 100 to the reference numerals used in Figs. 1 and 2. Thus, the motor H5 is mounted on the gear casing H0 to drive the shaft H6 by means of a worm and a worm gear H6. The lifting drum i221 has a peripheral groove which, as shown in Fig. 2, has different radii at axially spaced points. In this embodiment, however, there is provided an outer cylindrical section 150 in addition to the sections :24, $26 and 25.

When the motor is so operated by suitable actuations of the switch in casing 37 as to lower the load, the bias of the spring 34 is increased. Hence, when the load will be lifted, the spring will assist the electric motor operated in the opposite direction of rotation and thus render it possible for an electric motor with a limited power to lift a much higher load than it could do in the absence of the spring, provided the motor is reversible. In this manner, the present invention makes it possible to equip a hoist of a given load lifting capacity with an electric motor of but half the normal size, thus reducing both the cost of manufacture of the hoist and its power consumption which is extremely important in workshops where a great number of hoists are installed. Where A. C. motors are chosen and are to be installed in a workshop provided with a three-phase main line, it is recommended, in order to obtain a uniform load on the main, to split up the hoists in three groups connected between the three phases,

As a result of the difference in the diameter of the

drum section

24, 25 or I24, I25, 50 respectively, the load will be operated at different speeds when passing through different zones of elevation. That is illustrated in Fig. 4 with reference to the hoist shown in Fig. 3, the lifting speed of the load being shown as a function of the elevation of the load. Thus, it will be noted that the lifting speed amounts to 0.185 meter per second when the load is lifted between A and B from the floor up to an elevation of 0.4 meter and that then the lifting speed drops to 0.08 meterv from .B to C, while the rope l2? enters the spiral section of the groove provided on the conical intermediate section l28 of the lifting drum I22. While the load is lifted from a level 1.1 meters above the floor up to 1.75 meters, the lifting speed is kept constant at 008 meter per second. Then the lifting speed is slightly increased between D and E, while the rope ascends the section 150 of the drum. Between the level 1.85 meters and 2.2

meters above the floor the lifting speed amounts to 0.115 meter per second.

The present invention is primarily applicable to cases where a reduced lifting speed, the socalled fine adjustment speed, is required within a certain range of elevations only. That applies for instance to hoists used to carry a work-piece that is to be mounted on a tool-machine, for instance on the spindle of a lathe. In that case the fine adjustment speed is needed at an elevation of from 1 to 1 meters. When the requirements of any particular case are known, the drum may be easily so designed as to meet such requirements. Another case to which the present invention is applicable with great advantage is the lifting of holders out of a vat containing a chemical or a dye or the like. In that case a small lifting speed of the holder is required within a certain range only.

While I have described my invention with reference to two preferred embodiments thereof, I Wish it to be clearly understood that the same is not limited to the details thereof but is capable of numerous modifications within the scope of the appended claims.

What I claim is:

1. A hoist of the character described comprising a supporting structure, a horizontal bearing carried thereby, a shaft mounted in said bearing, a worm gear splined to such shaft adjacent to said bearing, a worm journalled in said supporting structure and engaging said worm gear, an electric motor mounted on said supporting structure in a driving connection with said worm. a lifting drum mounted on one end of said shaft, a spiral spring mounted on the other end of said shat t, and 9, spring barrel surrounding said spring and attached to said supporting structure.

2. A hoist of the character described comprising an overhead supporting structure, a pair of spaced co-a-xial horizontal bearings carried thereby, a shaft mounted in said bearings, a worm gear splined to said shaft between said bearings, a substantially horizontal worm journalled in said supporting structure and engaging said worm gear at the top thereof, a reversible electric motor mounted on said supporting structure co-axially and in driving connection with said worm, a lifting drum mounted on one end of said shaft, said lifting drum having adjacent cylindrical sections of different diameters and a transitional conical section therebetween and a single peripherai groove extending over said cylindrical sections and said transitional conical section for accommodating a lifting rope, a spiral spring mounted on the other end of said shaft, and a spring barrel surrounding said springand adapted to be attached to said supporting structure in different angular positions.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 152,145 McGlashan June 16, 1874 479,136 Ethridge July 19, 1892 1,015,459" Riggle Jan. 23, 1912 1,464,294 Reese Aug. 7, 1923 1,522,047 Cragun Jan. 6, 1925 1,529,796 Kalbach Mar. 17, 1925 1,926,452 Norling Sept. 12, 1933 1,928,532. Gillespie Sept. 26, 1933 2,323,404 Kuchar July 6, 1943 2,342,020 Stevens Feb. 15, 1944 2,481,037 Pringle Sept. 6, 1949