US 2074695 A
Description (OCR text may contain errors)
March 23, 1937. j F. A. JrMERsoN 2,74,695
HoIsT Filed oct. 10, 1934 5 INVENTORI` jHfdArroRNEr Patented Mar. 23, 1937 UNITED STATES PATENT OFFICE HOIST Application October 10, 1934, Serial No. 747,703
This invention relates to'hoists, and more particularly to hoists` of the double drum type in which the drums serve alternately as haulage and tail-rope drums, both being driven by a common drive shaft to which they are connected by clutching mechanism keyed to the drive shaft and shiftable from one drum to the other.
'I'he invention is of particular advantage when used in connection with hoists in which the alter- 10 nate functions of the drums take place in rapid succession and are continued for prolonged periods of time, and in which case it would be impractical to resort to the use of manually operable braking devices for controlling the rotational 5 speed of the drums. This is particularly true in elds o-f service where it is essential that a suitable tension be constantly maintained on all portions of the cable extending from one drum to the other, as for example, when the cable is used to reciprocate a cutting element of the type employed for sawing off pillars of self-material in mines.
In work of this nature it is 'customary to so arrange the cutting element as to initiate the 5 kerf on the far side of the pillar and, by alternately connecting the drums to the drive shaft, to pull the cutting element to and fro by means of the cable for severing the pillar. The reciprocations of the cutter take place in rapid succession, and in the absence of suitable means for preventing `unauthorized unwinding movement of the drums the cutting element and the unwound portions of the cable will sag and cause an objectionable whipping action of these elements at the 35 beginning of the subsequent cutting movement.
It is accordingly an object of the present invention to constantly maintain a suitable working tension on all portions of the unwound section of the exible element actuated by the drums.
40 Another object is to compensate for differences in the pitch diameters of the winding and unwinding layers of the flexible element of the several drums in order to maintain the correct tension on the tail end of the exible element.
45 Still another object is to automatically subject either drum to a force opposing unwinding rotational movement of either drum accordingly as one drum or the other serves as a tail-rope drum.
50 Other objects will be in part obvious and in part pointed out hereinafter.
The accompanying drawing is a plan view, in section, of a double drum hoist constructed in` ac- 'cordance with the practice of the invention.
55 Referring more particularly to the drawing, 20
designates, in general, `a hoist and 2l a pillar of material such as is commonly left standing in mines to support the. ceiling.`
The hoist comprises the usual base 22 and standards 23 which serve as bearings for a drive shaft 24. The drive shaft is provided with a gear 25 keyed thereto to mesh with a pinion 26 of a uni-directional motor 21. Y
Mounted on the drive shaft, and for free rotation thereon, are drums 28 and 23 on which are wound the ends of a cable 30 having interposed intermediate the ends thereof a flexible cutting element 3|. The cutting element may consist of a series of alternately arranged cutters 32 and spacers 33 for cutting a gash through the pillar 15 2| to sever it from the mass.
On the confronting ends of the drums are clutch members 34 and between the clutch members, and
vkeyed to the shaft whereon it is slidable, is a sleeve 35 carrying lclutch teeth 36 at each end for engagementr with the clutch members 34 of the 20 drums. The sleeve 35 carries a ring 31 disposed rotatably thereon and having trunnions 38 to engage a yoke 39 pivoted on the base 22. The sleeve 35 may be conveniently shifted into engagement with the clutch members 34 by a manually operable lever 40 connected to the yoke 39 through a link 4I.
In accord-ance with the practice of the invention, the hoist is provided with means for retaining the portion of the cable 30 serving as a tailrope under a tension capable of maintaining the trailing end of the cutting element substantially in the plane of its active cutting portion. To this end the drums 28 and 29 are provided on their outer ends with sprockets 42 to accommodate link chains 43 which are trained over sprocket wheels 44 keyed to the outer ends of shafts 45 and 46.`
The shafts 45 and 46 lie in parallelism with the drums 28 and 23, respectively, and are in coaxial alignment with each other. The shafts are supported by a bracket 41 secured to the base 26, as by bolts 48, and their outer ends seat in antifriction bearings 49inserted in the ends of the bracket 41. y
On the inner or adjacent ends of the shafts 45 and 46 is a differential gear train designated, in its entirety, by 50 and comprising the usual driving gears 5| which are keyed to the shafts and mesh with idler gears 52 mounted on a common 50 spindle 53. The spindle is supported by a rotatable carrier frame 54 in a well known manner adapted to cause the gears 52 to rotate about the axes of the shafts 45 and 46. On the carrier frame are trunnions 55 which encircle the shafts 55 the correct tension on the tail end of the cable 30 is maintained, may be supplied by any suitable device, as for instance an electrical motor 51 having a pinion 58 which meshes with a ring gear 59 on the carrier frame 54. The motor has a direction of power rotation opposed to the direction of pull of the carrier frame and is of a power capable of affording sufficient resistance thereto to prevent free unwinding movement of the tail-rope drum and thus maintain the tailrope end of the cable taut.
The motor 51 must be of thetype known as a torque motor which stalls Without damage when a definite torque is reached, or which may even be run backward when external torque applied thereto exceeds the stalling torque of the motor. A compressed air motor is a good example of this type. It will be seen that when the clutch sleeve is in a neutral position the motor 51, driving through the differential train will tend to rotate both drums to wind the cable 30 thereon. When, therefore, the driving motor 21 is connected through the clutch 35 to either drum the torque motor 51 opposes the unwinding tendency of the free drum Whether the unwinding tendency is due to pull on the cable, as is the case when there is a greater number of layers of cable on the haulage drum than on the tail rope drum, or due to the drive through the differential train when the contrary condition exists.
The operation of the device is as follows: With the drum 29 clutched to the shaft, and the motors 21 and 51 connected to a source of power, the cable 30 will be unwound from the drum 28 and wound onto the drum 29 to draw the cutting element 3| through the pillar 2|. When the trailing Vend of the cutting element 3| approaches the pillar the sleeve 35 -is shifted, by means of the lever and connected linkage, out of engagement with the drum 29 and into engagement with the clutch members 34 of the drum 28. The cable will then be unwound `from the drum 29 and wound onto the drum 23 to draw the cutting element 3| in the opposite direction. This operation is repeated until a kerf has been cut entirely through the pillar.
During this operation, of course, the number of layers of cable on the drums constantly varies so that in certain positions of the cutting element relatively to the work only one layer of coils may remain about the drum 29 while a plurality of layers of cable may lie on the other drum. It is obvious, therefore, that the pitch diameters of the active coils and the speeds of the drums differ throughout a run of winding and unwinding coils and necessarily vary at the beginning and ending of a layer of coils. Further, that when the active coils are of the same pitch diameter both drums will operate at the same speeds, as is of course understood. In the latter case the carrier frame remains stationary, but when the drum speeds differ it will be rotated by the motor or will cause the motor to rotate to serve its well known function, the effect of which, in the present instance, is to maintain tension in the tail end of the cable.
By the application of the differential gearing and a suitable power device or Weight acting thereon the speed adjustments between the drums, that is, the retention of a correct ratio of speed between the drums may be maintained without necessitating manual attention or without adding materially to the cost of operation of the hoist.
1. A hoist, comprising a drive shaft, a pair of drums, means for connecting the drums alternately to the drive shaft, a cable having its ends connected to the drums to be wound thereon, a differential gear train, driving connections between the drums and the driving gears of the train, and a motor connected to the ring gear of the train and having a direction of power rotation opposed to the direction of pull of the ring gear.
2. A hoist, comprising a drive shaft, a pair of drums thereon, means for causing each drum to serve alternately as a haulage drum and a tailrope drum, a flexible element having its ends connected to the drum to be wound thereon, and driving means independent of the drive shaft continuously acting upon both drums to prevent slack in the tail end of the flexible element.
3. A hoist, comprising a drive shaft, a pair of drums thereon, means for causing each drum to serve alternately as a haulage drum and a tailrope drum, a cable having its ends connected to the drums to be wound thereon, differential gearing having its driving gears connected to be driven by the drums, and driving means independent of the drive shaft constantly opposing rotary movement of the driven gears of the differential gearing about the axes of the driving gears, thereby preventing free rotation of the tailrope drum and maintaining tension upon the tail-rope.
4. A hoist comprising a drive shaft, a pair of drums thereon, means for causing each drum, to serve alternately as a haulage drum and a tailrope drum, driving means independent of the drive shaft comprising differential gearing, means for transmitting the movement of the differential gearing to the drums, and a motor constantly acting on the differential gearing to apply a force to oppose unwinding movement of the drums.
5. A hoist comprising a drive shaft, a pair of drums freely rotatable thereon, means connected I to the drive shaft for selectively transmitting the motion thereof to the drums, a cable having an end connected to each drum, a differential gearing having driving and carrier gears, means connecting the drums to the driving gears thereof, and motor means connected to the carrier gear thereof and constantly opposing the unwinding movement of the drums, whereby tension is continuously maintained upon the cable of the idle drum.
6. A hoist comprising a drive shaft, a pair of drums, means for selectively driving one of the drums by the shaft, a cable member having its ends connected to the drums to be wound thereon, a differential gear train, driving connections between the drums and the driving gears of the train, and motor means coacting with the ring gear of the differential train to oppose unwinding of the free drum.
FRANCIS A. JIMERSON.