US853733A - Elevator safety device. - Google Patents

Description

iATENTED MAY 14, 1907. S

0. R; PRATT. ELEVATOR SAFETY DEVICE.

APPLICATION FILED un..s,19o5.

4 SfiEBTS-SHBBT 1.

. WITNESSES INVENTOB;

' mm N 3273M! @MMMW ATTORNEY.

THE NaRRIs PETERS C0,, WASHINGTON, D, C4

PATBNTED MAY 14', 1907.

No". 853,733. v

' c. PRATT.

. ELEVATOR SAFBTY'DEVIGE.

APPLICATION FILED APR. 3, 1905 4 SHEETS-SHEET a.

' INVENTOII WITNESSES I ATTORNEY TH'E Nckms pznms ca., WASHINGTON, n. c.

PATENTED MAY 14, 1907, v

c. R. PRATT. ELEVATOR SAFETY DEVICE. A PPLIOATIOIIILBD APILS, 1905.

4 SHEETS-SHEET s.

i E I m PATENTBD MAY 14, 1907.

0. R. PRATT. ELEVATOR SAFETY DEVICE.

AP PLIOATION TILED APR 1905.

4 SHEETS SHEET 4.

INVENTOR? 7D ATTORNEY THE uomws PEIERS co. \vasnmaron, u. c.

A w i ,w

WITNESSES- AMM i m BY 1% mmm STATES PATENT OFFICE.

ELEVATOR SAFETY DEVICE.

Specification of Letters Patent.

Patented May 14, 1907.

Application filed April 3, 1905- Serial No. 253,437-

To on whom, it may concern:

Be it known that 1, CHARLES R. PRATT, a citizen of the United States, residing at Montclair, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Elevator Safety Devices; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters of reference marked thereon, which form a part of this specification.

This invention relates to safety devices for elevators, and more particularly to such safety devices as have jaws located on the car and which are adapted in case of accident to grip rails or the like arranged vertically or longitudinally of the hoist-way.

The objects of the invention are to employ a differential screw for actuating the gripping jaws; to thus secure longitudinal movement of the screw shaft as a whole; to enable the rope drum to be mounted directly upon the said screw shaft and thus partake of its said mption; to thus avoid angular deflection of the rope leading to said drum as it winds or unwinds and enable an idler' sheave to be placed close to the drum to automatically insure that the differential screw shall act by the full pitch of one of its ends until the gripping jaws come in contact with the rails and then close said jaws upon the rails bythe differential action of its two ends; to thus secure a rapid movement of the gripping jaws up to or against the rails, so that no time will be lost in getting them into gripping relation after the car begins to fall; to con 'trol such change of action by the act of engagement of the gripping jaws with the rails; to thus regulate the power applied to the jaws by the necessity for such power or the work which is to be done; to provide upon the screw shaft detent means for ordinarily preventing the said shaft from rotating, and to obtain other advantages and results, some of which wi ll be hereinafter referred to in connection with the description of the working arts. p The invention consists in the improved safety device for elevators, and in the arrangements and combinations of parts of the same, all substantially as will be hereinafter set forth and finally embraced in the clauses of the claims.

Referring to the accompanying drawing, in which like letters of reference indicate corresponding parts in each of the several figures, Figure 1 is a side elevation of an elevator car and its safety device attachments complete; Fig. 2 is a rear elevation of the safety device mechanism at the bottom of the car; Fig. 3 is a view looking upward from beneath the car and showing one end portion of the safety mechanism, partly in central longitudinal section; Fig. 4 is a continuation of Fig. 3 showing the drum end of the said mechanism, also partly in section; Fig. 5 isa detail view of a pair of the gripping jaws in side elevation; Fig. 6 isa detail plan of certain pawls, and Fig. 7 is a section of the same on line ac, Fig. 6.

In said drawings, 2 indicates an elevator car of. any well-known construction adapted to move between rails arranged longitudinally of the hoistway at opposite sides thereof, the rails 3, 3, shown in the drawings being rigid T-rails each having its rib or stem portion 4, next to the car. I

Upon the car, preferably at its bottom, are arranged means for automatically gri ping the said ribs 4, of the rails 3, in case 0 accident, so as to bring the car to a gradual stop. These gripping means are supported upon the bottom of the car by depending brackets 5, 5, having their lower ends braced by a cross rod 6, extending therebetween. Upon the said ends of the brackets 5, are pivoted opposing quadrangular or bell-crank levers 7, 7, adapted at their jaws 8, to bite against the opposite sides of the rib 4, of the T-rail, and having their other faces 9, projecting substantially at right angles on opposite sides of the brackets and their connecting rod 6. Furthermore, upon each end of the said rod 6, is mounted a sleeve 10, or 100, adapted to slide on the rod and having at its outer end sideextensions 11, 11, (or 101, 101) adapted to engage the said levers 7, 7, and force them against the rail 3.

The rod 6, carries upon itself intermediate of its ends and of the sleeves 10, 100, just described, a'hollow shaft 12, which has at its opposite ends threads of the same kind or diential screw is provided. One end of this hollow shaft, as 13, receives a correspondingly threaded nut 14, which is bolted to the sleeve 100. The other end 15, of the said shaft also receives a correspondingly threaded nut 16, which nut telescopically enters therection but differing in pitch, so that a difier- ITO 'tremity of the same.

adjacent end of the sleeve 10, and has an annular rib or flange 17, to bear against the ex- The inner end 18, of the nut 16, is then provided with spring controlled pawls 19, adapted to normally lie in pockets or recesses 20, of the hollow shaft 12.

A rope drum 21, is fixed upon the said hollow shaft 12, and said drum has oppositely wound upon itself and anchored thereto, the ends 22, 23, of a governor rope 24, which ends pass outward over an idler sheave 25, upon the edge of the elevator car 2, one extending upward over a governor sheave 26, and the other downward over the tension sheave 27, and the two meeting to form a closed loop of rope. Under normal conditions, the drum 21, is held from turning by means of spring pawls 28, upon the nut 14, and which engage pockets 29, in the outer surface of the hollow shaft. In this relation of parts, the rope 24, runs idly over the governor and tension sheaves 26, 27. If, however, an accident occurs so that the car starts to drop and the governor sheave 26, rotates at a speed above the normal, centrifugal weights 30, on said sheave fly outward and trip a latch 31, to release the same and permit a movable jaw 32, to clamp the rope 24, against a cooperating fixed jaw 33. Obviously this stops movement of the rope 2 1, with respect to the governor and tension sheaves, and the drum 21, begins to turn, one end of the rope unwinding therefrom and the other end winding upon the drum. When the drum thus begins to turn, the pawls 28, are forced out of their seats and ride upon the outside of the hollow shaft.

When in case of an accident the hollow shaft 12, thus turns, obviously the nut 16, will be held to the shaft by means of its pawls 19, and will turn with the said shaft loosely in the end of the adjacent sleeve 10, there being no pressure upon the jaws to retard the sleeve at this moment. This insures that the screw threads at that end of said shaft are idle and the full effect of the opposite threaded end 13, of the shaft is utilized to throw the gripping jaws 7, 7, against the rails 3, 3. In other words, when the safety device comes into action, the differential screw feature does not at first operate an d the jaws 7, are thus quickly carried into contact with the rails 3. When such contact is effected however, the pressure of the jaws creates an end thrust of the sleeve 10, against the annular flange 17, of the nut 16, and causes a friction which overcomes that of the pawls 19, in their pockets. Said pawls are therefore forced out of their seats, and the hollow shaft begins to turn in the nut 16, said nut becoming stationary with respect to the sleeve 10. The differential screw feature is therefore now brought into play and the aws at the opposite sides of the elevator car are forced into intimate relation to the rails gradually and with such pressln". as may be desired.

Upon releasing or reversing the hollow shaft 12, the nut 16, remains statiomiry with respect to the sleeve 10, until the friction between said nut and the sleeve relaxes sufficiently to let the nut turn with the shaft. To insure that this shall not happen until the pawls 19, have reached their pockets, l er ate additional friction between the nut 16, and sleeve 10, by means of a ring 31, slidably mounted upon bolts 35, which project from the end of the sleeve outside the flange 1 7, and which ring is pressed by springs 36, against the opposite side of said flange from the sleeve 10.

The pawls 19, (and 28) may obviously be of any suitable and well-known construction, but preferably each of the pawls is pivoted to lugs 37, upon the nut and curved part way around the same as shown. T he free end 33, of each pawl is held by a spring 39, to the pivot of the other pawl, and intermediate of its ends the pawl has a projection adapted to extend through the wall of the nut into the pockets of the hollow shaft, and which may be either integral with the pawl bod as at 40, in Fig. 4, or separably secured thereto as at 41, in Fig. 3.

It will be understood that the term rails as used herein refers to and is intended to include not only the T-rails shown, but also any known form of guide rails, the tension strips shown in my co-temporaneous application filed March 27, 1905, Serial No. 252,150, or any other support; adapted to be frictionallyengaged by means on the ear, the gripping jaws being any such means as just mentioned which will engage cot'iperating rails and can be operated by my differential screw construction and, the term differential screw is employed to designate a shaft having at different longitudinal portions of itself threads of the same kind or direction but of different pitch.

By using the differential screw which .l. have shown, it will be noted, first, that the time occupied by the gripping jaws in engaging their rails may be regulated by the differ ence in pitch between the two threaded portions of the screw shaft, and thus the governor-rope drum can be mounted directly upon the said shaft without the intervention of gearing such as shown in my prior application, Serial No. 252,150, filed March 27. 1905; and second, that longitudinal movement of the screw shaft as a whole, (and therefore of the drum). is secured, with respect to the elevator car, in operating the gripping devices. The first of these points requires the use of the idler sheaves 25, Fig. 1, at the edge of the car, but the second point insures that by a proper calculation of the pitch of the threads on the screw shaft, the drum shall move just enough as its rope ends Having thus described the invention, wh at I claim as new is 1. In an elevator safety'device, the combination with hoistway rails, of sets of friction members adapted to engage one each of said rails, a shaft having upon different longitudinal portions of itself exterior threads of the same kind or direction but of different pitch, means engaging one of said threaded portions and being'non-rotatably connected to the adjacent set of friction members, similar means engaging the other threaded portion of the shaft and rotatably engaging its adjacent set of friction members, and means for automatically turning said shaft upon falling of the car.

. 2. In a safety device for elevators, the combination with hoistway rails, of friction members adapted to engage said rails, a shaft having upon different longitudinal portions of itself exterior threads of the same kind or direction but of different pitch, nuts upon said threaded portions of the shaft, means adapted to non-rotatably transmit motion from one of said nuts to its adjacent,

friction member and means for rotatably transmitting motion from the other nut to its friction member, and means automatically operated by the falling of the car to turn said shaft.

3. In a safety device for elevators, the combination with hoistway rails, of friction members adapted to engage said rails, a shaft having differentially threaded portions, nuts upon said shaft, means adapted to transmit motion from said nuts to the friction members, and means adapted to be automatically operated by falling of the car to rotate said shaft.

4. In a safety device for elevators, the combination with fixed hoistway rails, of brackets adapted to depend from a car, a rod extending betweensaid brackets, a hollow differential screw shaft upon said rod, nuts upon said shaft, friction members adapted. to be operated by said nuts to engage the hoist way rails, and means adapted to be automatically operated by falling of the car to rotate said shaft.

5. In an. elevator safety device, the combination with hoistway rails, of sets of friction members adapted to engage one each of said rails, a shaft having upon opposite end portions of itself threads of the same kind or direction but of different pitch, non-rotatable means engaging one of said threaded portions and transmitting its longitudinal motion to one set of friction members, and other rotatable means having a frictional engagement with the shaft to turn therewith and with the adjacent friction members to impart longitudinal movement thereto.

6. In an elevator safetydevice, hoistway rails, friction members adapted to grip said rails, a shaft having upon different longitudinal portions of itself exterior threads of the same kind or direction but of different pitch, means for transmitting motion from said threaded shaft portions to the friction members, and a governor rope drum mounted directly on the shaft and having rope grooves of substantially the same pitch as one of the said threaded portions of the shaft.

7. In an elevator safety device, the combination with hoistway rails, of sets of friction members adapted to engage one each of said rails, a shaft having upon different longitudinal portions of itself exterior threads of the same kind or direction but of different pitch, means engaging one of said threaded portions and being non-rotatably connected to the ad j acent set of friction members, similar means engaging the other threaded portion of the shaft and rotatably engaging its adjacent set of friction members, and a governor-rope drum mounted directly on the shaft and hav ing rope grooves of substantially the same pitch as the threaded shaft-portion whose said engaging means are non-rotatable.

8. In an elevator safety device, hoistway rails, gripping jaws adapted to engage said rails, a differential screw for operating said jaws, and a governor-rope drum mounted directly upon said screw shaft. I

9. In an elevator safety device, hoistway rails, gripping jaws adapted to engage said rails, a differential screw for operating said jaws, and a governor-rope drum mounted upon said shaft andhaving peripheral rope grooves of substantially the same pitch as one of the threaded portions of the screw.

10. In an elevator safety device, hoistway rails, gripping jaws adapted to engage said rails, a differential screw, nuts upon said screw one of which is made fast to its adjacent gripping jaws and the other of which has a frictional connection to its adjacent gripping j aws, and a governor-rope drum on said shaft having rope grooves of substantially the same pitch as the threaded screw portion which has the said nut made fast to the gripping jaws.

11. In an elevator safety device, hoistway rails, gripping jaws adapted to be mounted on a car and engage said rails, 'a differential screw and nuts for operating said jaws, and means for causing one of said nuts to either turn with the screw or be stationary with respect thereto as desired.

12. In an elevator safety device, hoistway rails, gripping jaws adapted to engage said IIO rails, a' differential screw and nuts for operating said jaws, means for imparting motion to the screw with respect to one of the nuts, and other means adapted to be operated as a result of such motion to cause the other nut to either turn with the screw or be stationary with respect thereto as desired.

13. In an elevator safety device, the combination with rails for the opposite sides of the hoistway, of opposite gripping jaws adapted to be mounted on a car and engage said rails, an intermediate differential screw, a nut on one end of said screw fixed against rotation with the screw and adapted to transmit its longitudinal motion to the adjacent jaws, and a second nut on the other end which may either turn with the screw or remain as to rotation independent of such turn ing.

14. In an elevator safety device, the combination with rails for the opposite sides of the hoistway, of opposite gripping jaws adapted to be mounted on a car and engage said rails, an intermediate differential screw, a nut on one end of said screw fixed against rotation with the screw and adapted to transmit its longitudinal motion to. the adjacent jaws, and a second nut on the other end adapted to frictionally transmit its longitudinal motion to its adjacent gripping jaws.

15. In an elevator safety device, hoistway rails, friction members adapted to engage said rails, a shaft having differentially threaded portions adapted to operate said friction members, detent pawls projecting from a non-rotary support and adapted to engage the said shaft to normally prevent its turning, a governor-rope drum fast on said shaft, and a governor.

1.6. In an elevator safety device, the combination with hoistway rails, of members adapted to engage said rails, a shaft having upon different longitudinal portions of itself exterior threads of the same kind or direction but of different pitch, and means upon each of said threaded portions connecting the same with its adjacent gripping member, one

of said means engaging its gripping member frictionally and being adapted to remain stationary with respect thereto or to turn with the shaft according to the relative friction of said. parts.

17. In an elevator safety device, the combination with hoistway rails, of gripping members adapted to engage said rails, a shaft having upon different longitudinal portions of itself exterior threads of the same kind or direction but of different pitch, and nuts upon said threaded portions adapted to engage the gripping members, respectively, one of said nuts engaging its adjacent gripping member frictionally and being adapted to remain stationary with respect thereto or to turn with the shaft according to the relative friction of said parts.

18. In an elevator safety device, the combination with hoistway rails, of gripping members adapted to engage said rails, a shaft having upon different longitudinal portions of itself exterior threads of the same kind or direction but of different pitch, means engaging one of said tlll:ltl((l portions and being held against rotation with the shaft, and other means engaging the other thremhal portion and being free to either turn with the shaft or remain imhepeudent of it as to rotation, both said means transmitting longitudinal motion to the gripping members.

19. In a safety device for elevators, the combination with hoistway rails, of gripping jaws adapted to be mounted on the ear aml engage said rails, a differential screw adapted to act by one threaded portion alone to rapidly advance the gripping jaws toward the said rails and by the joint effect of both threaded portions to force the gripping jaws into engagement with the rails, and means for operating said screw.

20. In an elevator safetydeviee, hoistway rails, gripping jaws adapted to engage said rails, an intermediate threaded shaft to operate said jaws, two nuts mounted on said shaft, means adapted to secure relative rotation of the shaft whereby longitudinal motion is transmitted to the jaws, and means for causing one of the nuts to turn with the shaft and to I'Oll'litlll stationary as to rotation at different sta es of action.

21. In a safety device for elevators, the combination with lmistway rails and jaws adapted to grip said rails, of a differential screw between said jaws, a nut on one end of said screw fixed againstrotation and adapted to transmit longitudinal motion to tl i adjacent jaws, and a second nut on the other end rotatable with the screw and adapted to transmit its longitudinal motion to the adjacent jaws through a frictional thrust bearing.

22. In a safety device for elevators, the combination with hoistway rails aml jaws adapted to grip said rails, of a differential screw between said jaws, a nut on one end of said screw fixed against rotation, and a second nut on the other end adapted either to turn with the screw or remain independent of it as to rotation, both said nuts transmitting their longitudinal motion to the gripping aws.

23. In a safety device for elevators, the combination of a car, hoistway rails, gripping jaws mounted on the air and adapted to engage said rails, a differential screw to operate said gripping jaws, a winding rope drum mounted on said screw, and idler sheaves on the car, whereby the longitudinal axial motion of said screw and drum pays the rope on said drum to and, from said idler sheaves without angular dell ction in the l Fad of the rope.

In an elevator safety device, hoistway lOC llC

rails, gripping jaws adapted to engage said rails, an intermediate threaded shaft to operate said jaws, two nuts mounted on said shaft, means adapted to secure relative rotation of the shaft whereby longitudinal motion is transmitted to the jaws, and frictional means for causing one of the nuts to turn with the shaft and to remain stationary as to rotation at different stages of the action.

25. In an elevator safety device, hoistway rails, gripping jaws adapted to engage said rails, an lntermediate differential screw to operate said jaws, means for rotating said screw, and two nuts 011 said screw adapted 15 to engage said aws, respectively, one of said nuts engaging its adjacent jaw frictionally and being adapted to remain stationary therewith or to turn with the screw according to the relative friction of said parts.

In testimony,that I claim the foregoing, I have hereunto set my hand this first day of April 1905.

CHARLES R. PRATT.

Witnesses:

RUSSELL M. EVERETT, M. V. DOYLE.

Images