US1625084A

US1625084A - Roping for hoisting apparatus

Info

Publication number: US1625084A
Application number: US737300A
Authority: US
Inventors: Hymans Frederick
Original assignee: Otis Elevator Co
Current assignee: Otis Elevator Co
Priority date: 1924-09-12
Filing date: 1924-09-12
Publication date: 1927-04-19
Anticipated expiration: 1944-04-19

Description

1927. F HYMANS ROPING FOR HOISTING APPARATUS Filed SeDt. 12, 1924 April 19 Patented Apr. 19, 1927.

EJNHTED STATES FREDERICK HYMANS, OF YONKERS,

PANY, OF JERSEY CITY, NEW JERSE NEW YORK, ASSIGNOR TO OTIS ELEVATOR COM- Y, A CORPORATION OF NEW JERSEY.

ROIPING FOR HOISTING APPARATUS.

Application filed September 12, 1924. Serial No. 737,300.

This invention relates to the roping employed in connection with hoisting apparatus of the type in which the weight of a load carrying device suspended from a drum or sheave is balanced at least partly by a counterweight.

The principle of this invention involves the provision of means for causing the travel oi the counterweight to be less than the travel of the load carrying device, but in some proportion thereto.

The invention will be described, as applied to an elevator system, in connection with the accompanying drawing in which,--

Figure 1 is a schematic view of anelevator system employing chain compensation and en'ibodying the invention,

Figure 2 is a. schematic view of an embodiment of the invention as applied to an elevator system employing rope compensation.

Referring to the drawings, a cage 1 is shown suspended by rope 2 which passes over an upper grooved sheave 3, then downwardly around a sheave 4'and from sheave 4 to a hitch 5 secured in fixed position at the upper end of the hoistway. Sheave 4 is secured to shaft. 6 which is rotatably mounted at the upper end of an extension of the frame of counterweight 7. It will readily be seen that, as sheave 3 is rotated to raise or lower cage 1, counterweight 7 moves one-half as far as cage 1 and at onehalr" its speed. If it is desired to balance the weight of cage 1 exactly, the weight of counterweight 7 is made equal to twice the weight of cage 1. For example, assume that cage 1 is lowered from the position shown at the 4th floor to the 1st floor, counten weight 7 moves up half the distance between the 1st and 4th floors. Further assume that the cage moves at a. speed of 800 feet per minute and that its weight is 3000 pounds. The weight of counterweight 7 required to balance the weight of cage 1 will then be 6000 pounds and the counterweight will travel at the rate of 400 feet per minute.

Calculating the kinetic energy we find Kinetic energy of cage:

BZ QL 5% :8292 foot'pounds 2X32.16 6O Kinetic energy of counterweight:

X i l 2 :4146 foot pounds 2X32.16

Total kinetic energy of cage and counterweight:

8292+4146:12438 foot pounds.

2 2 oot pounds Kinetic energy of the counterweight w gg) 2 8292 foot pounds 21132.16 60 Total kinetic energy of cage and counterweight:

8282+8292:16584 foot pounds.

From the above it is seen that when using a roping according to the assumed example the reduction in kinetic energy of the cage and counterweight amounts to 1658412438:: 4146 foot pounds or 25 per cent. This re duction in kinetic energy has many advantages among which are a corresponding decrease in time of starting and stopping for the same torque on the hoisting sheave and less liability of slipping the ropes in starting and stopping with a. given acceleration and retardation.

In Figure 1 a compensating chain {-5 is shown as attached at one end to the cage and at the other end to a fixture 9 located near the center of travel of the cage. The weight of chain 8 is so selected that as the cage is raised and lowered, the change in weight of rope 2 (for which a plurality oi ropes may obviously be substituted it clesired) is compensated for by change in weight of chain 8, so that the weight suspended from sheave 3 on the cage side is constant at all points of travel for the same load in the cage. A second chain 10 hangs between counterweight 7 and a fixture 11 preferably located at a point one-quarter of the distance from the lower floor to the top floor, which location minimizes the length of chain required, since the travel" of the counterweight is one-half the travel of the The weight of chain 10 is made such that it compensates for the change in weight of the portion of rope 2 on the counterweight side of sheave 3 so that the weight suspend-ed on that side isat' all times constant. r

It is to be noted that inlroistingappara tus according tothis invention it isnecessary to install guide rails for the counterwei ht in the hoistway for a portion of its length only; V here the counterweight moves one-half the distance moved by the cage, as illustrated, the counterweiglit guide rails may be one-halt as long as the guide rails for the cage and located in such portion of the hoistway as maybe deeriied best.

In Figure 2 a compensating rope 12 ex;

e she I thence upwardly over sheave 15 mounted on the lower end of the frame of counterweight 7 and from there downwardly to a stationary hitch 16. The function of tension weight A is to maintain compensating rope 12 in its proper relation to cage 1 and counterweight 7 while at the same time taking up any slack that may occur due to stretching or wear of the various parts. Neglecting the slight changes in length of

ropes

2 and 12 due to stretching, it will be observed that sheave 13 will not move up or down as the cage is raised and lowered, but that the portion of compensating rope 12 between cage 1 and sheave 13 increases and decreases in length by the same amount as the portion of rope 2 between cage 1 and sheave 3 decreases and increases in length. In the same way the changes length of the portions of rope 2 between sheave 3 and sheave 4 and between sheave4- and hitch 5 are compensated for by the changes in lengthof the portions of rope 12 between sheave 13 and sheave l5 and between sheave l5 and hitch 16 respectively. Therefore the total weight suspended from sheave 3 is at all times equally divided between its two sides, for a given load in the cage." Rope Qand rope 12 are shown as single ropes but obviously either may be replaced by several ropes, it

being necessary, if it is desired to effect full compensation, to have the weight of the hoisting ropes equal to the weight of the compensating ropes per unit length.

VVhat is claimed is 1. Hoisting apparatus comprising a cage, a counterweight therefonoperating connections between cage and counterweight for effecting counterweight travel in unison with t nds from cage 1 downwardly under aave 13 mounted on tension weight lat,

cage travel'and at reduced ratio with respect thereto, and flexible means associated with the cage and counterweight for compensati'ng'for' the variation in the distribution of the weight of said Operating connections during the raising and lowering of the cage and counterweight.

2. Hoisting apparatus comprising a rope secured at one end to a fixed point, a cage suspended from the other end of said rope, a .drivingsheave over which said rope eX- tends from said cage, a counterweight having a, sheave hung in a dependent loop of said rope between said driving sheave and said fixed point, and counterbalance roping associated with the cage and counterweight and shilz'table to compensate torthe change in the distribution ot tlie weight of the supporting rope for the cage'and counterweight curing thet r'avel thereof. v

8. Hoisting apparatus comprising a cage, a counterweight therefor, roping connections for ei'le cting counterweight movement at reduced ratio with respect to the raising and lowering otfthe cage, and means for compensating for the variation in the distribution of the weight of the roping during the raising and lowering or the cage and counterweight.

4'. Hoisting apparatus comprising the combination with a cage, a counterweight, driving mechanism, roping supporting said cage and counterweight and comprising means for efiecting movement of said counterweight in reduced ratio to cage movement; of a compensating rope the entire length of which is supported by said cage and counterweight, and means for transfer ring from theone to the other the support of a length of compensating rope equal to the increase'in length of the ropes supporting the one and the decrease in length of the ropes supporting theother, during cage travel.

I 5. In hoisting apparatus, the combination with a cage, a driving sheave, a counterweight, a hoisting rope sheave on said counterweight, and a hoisting rope supporting the cage and extending continuously there from over said driving sheave and under said" counterweight sheave, of compensating means comprising a compensating rope sheave carried by said counterweight, a guide sheave, and a compensating rope extending continuously from the cage, under said guide sheave and over said compensating rope sheave carried by the 'coiinterweight.

In testimony whereof, I have signed my name to this specification. FREDERICK HYMANS.