US1032340A - Safety device for elevators. - Google Patents

Description

E. s. MATTHEWS. SAFETY DEVICE FOR ELEVATORS.

APPLICATION FILED DEC. 30, 1908.

1,032,340. Patented July 9, 1912.

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E. S. MATTHEWS.

SAFETY DEVICE? FOR ELEVATORS.

APPLICATION FILED DEC. 30, 1908.

Patented July 9, 1912.

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E. S. MATTHEWS.

SAFETY DEVICE FOR ELEVATORS.

APPLICATION FILED DEC. 30, 1908.

1,032,340. Patented July 9, 1912.

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EDWIN S. MATTHEWS, OF NEW YORK, N. Y., ASSIGNOR TO OTIS ELEVATOR COMPANY, OF JERSEY. CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY.

SAFETY DEVICE FOR ELEVATORS.

To all whom it may concern:

Be it known that I, EDWIN S. MATTHEWS, a citizen of the United States, residing in New York, in the county of New York and State of New York, have invented a new and useful Improvement in Safety Devices for Elevators, of which the following is a specification.

My invention relates to improvements in safety devices for elevators; and has for one of its objects the provision of means for quickly and powerfully clamping an elevator car to the guides over which it is adapted to travel should the car for any reason exceed a certain predetermined speed in any direction, the arrangement being such that the car is brought to rest before the same has acquired too much momentum.

A further object is the provision of a safety device of the guide clamping type, in which the gripping jaws are quickly applied to the guldes with a predetermined pressure and continue to tighten upon them and with increased power until the mo ment-um of the car is overcome and the latter comes to rest.

Other objects of my invention will appear hereinafter, the novel combinations of ele ments being pointed out in the appended claims.

A practical embodiment of my invention is represented in the accompanying drawings forming a part of this specification, in which like characters of reference denote corresponding parts in all of the figures.

Figure 1 is a diagrammatic viewin side elevation of an elevator car. and certain connected apparatus which may be used in carrying out my invention; Fig. 2 is a sectional plan view of the safety device; Fig. 3 is a transverse section on the line a-a of Fig. 2; Fig. 4 is a side elevation of Fig. 2; Figs. 5 and 6 are side section and end views, respectively, of a cable clamping device; Fig. 7 is a view in perspective of one of the traveling nuts; Fig. 8 is a view similar to Fig. 4, showing a modification; and Fig. 9 is a sectional side View of Fig. 8 upon the line bb looking in the direction of the arrows.

10 designates an elevator car, to the bottom of which my device is attached.

11 is a hoisting cable which is secured to the top of the car and connected to any desired hoisting apparatus.

Specification of Letters Patent.

Application filed December.30, 1908.

Patented July 9, 1912.

Serial No. 469,933.

12 is a govenor cable connected to run with the car. This governor cable runs under a sheave 20 located near one end of the cars travel. It may be weighted as at 22, and pawls 21, 21 may be provided, if desired, to engage with ratchets in the sides of the weight 22 to prevent its upward move ment. The governor cable 12 runs over another sheave 13 near the other end of the cars travel, which is connected to a governor or speed regulator 14 by suitable gearing 15. The governor 14 is arranged to actuate gripping devices 16, 16 which grip and positively lock the governor cable 12 whenever the car exceeds its normal speed. It may be regulated or set to operate at any desired speed, and may be arranged to operate when the car is running in either direction. The governor cable is yieldingly connected to the car at 17, and is so arranged that when the governor cable is stopped and the car continues to move it will pull awayfrom the yielding connection. This will cause the cable 18 which is attached to the governor cable 12 at 61 to be pulled through the pulleys 19, 19 and to be unwound from a drum 23 on the'safety device, and thereby impart a rotary motion to the winding drum.

It is sometimes desirable to operate the safety device by hand from the car, and for this purpose I have provided a ratchet lever in the car, by means of which the operator may at any time apply the safety device so as to retard the speed of the car or to bring the latter to a full stop.

I will now refer to the other figures, and describe the clamping or safety device which is there illustrated.

26 designates a framework of channel beam construction which carries the clamping apparatus and which is preferably secured to the bottom of the elevator car, although under certain conditions it may be located elsewhere. Since the various parts of the apparatus shown in Fig. 2 are symmetrically arranged with respect to a common central line, I will refer in the description to but one of the similar halves.

29 29 designate a pair of gripping members pivoted to the frame 26 at- 30 and provided at one end with clamping jaws adapted to engage adjacent sides of the guide rail 28, but normally out of contact therewith. The other end of the gripping members 29 forced between the rollers, thereby causing.

the clamping aws to move into engagement with the lateral surfaces of the guide rail 28. Normally the clamping jaws should be held wholly out of engagement with said guide rails by means of a spring, such as 33, acting on the gripping members 29, 29.

Rotatably mounted intermediate the fixed supports 42 and 42 is the safety drum 23, on which the cable 18 (Fig. 1) is wound. If desired, this drum may be grooved as shown to receive said cable, although under certain conditions the surface of the drum may be cylindrical. In either case the cable 18 is wound upon the drum several turns andhas its end secured thereto. The drum 23 is carried upon the left and right- hand screws 37, 37 which are adapted to rotate with the drum through the spline connection 27. The screws 37 and 37 pass loosely through the supports 42, 42 and are threaded into traveling nuts 38, 38, respectively. Each of these nuts, such as 38, is provided with guide portions 39, 39 which pass through corresponding slots in the support 42 and extend into an annular recess 40 formed in the drum. Between'each traveling nut and its corresponding support, a pair of similar wedges, such as 44 and 46, are located. Each of these wedges passes through slots 43 and 45 formed in the support 42 and the channel beams 26, 26, the slots being of sufficient length to allow for clearance when the wedges are moved into operative position. The faces of the wedges adjacent the support 42 are flat, while the faces in contact with the nut 38 are tapered or inclined to correspond to the inclined face 41 (Fig.v 7) of the nut. The angle of inclination of the engaging faces of the wedges and the traveling nut, where one face of each wedge is fiat as shown, should not as a rule exceed four degrees, although in some cases I contemplate using a greater or lesser angle of inclination. The wedges of each pair are secured at the bottom by a strut47 and through-bolt 48, and each pair of'wedges is connected at the top by means of bolts 49 to an off-set frame 50. This frame contains a slot 51, in which a cable clamp 53 is arranged to have a longitudinal movement only. The clamp is shown in detail in Figs. 5 and 6, and comprises a body portion of larger diameter than. that of the slot 51, and having a groove turned in the periphery of the clamp to receive the slot. The clamp has a tortuous hole through the center, which contains the cable 18 and a leaf spring 54. Set- screws 55, 55 bear against the spring 54, and by adjusting said without departing from the Spirit of this screws the frictional engagement between the clampand the cable 18 may be varied to any desired amount. It is evident that only a portion of the power of the governor cable is utilized to effect the quick motion of the slack take-up, and that other methods obviously might be employed for dividing a certain proportion of the power of the cable between the wedges and the drum invention. In order to insure that all of the wedges will be moved simultaneously, I provide. a squaring device comprising a shaft 56 supported in bearings 58, 58 upon the channel beam 26,. said shaft carrying upon either end a rigidly secured pinion 57 57 arranged to mesh with corresponding rack teeth 59, 59 cut in the wedges 44 and 44 The operation of the apparatus thus de scribed is as follows: As soon as the elevator car exceeds a certain predetermined speed in either direction, the governor 14 operates to lock the governor cable 12 against further movement. As the car continues to move, the cable 18 is pulled between the pulleys 19,19, carrying with it the frame 50 to which the wedges are fastened, and

also at the same time causing the drum 23 and screws 37 37 to rotate. As the wedges move upwardly (Fig. 2), the traveling nuts 38 and 38, together with the screws 37, 37 are moved outwardly, forcing the wedges 31, 31 between the rollers 34, 34 and 34, 34, respectively, thereby clamping the gripping jaws at either end of the safety device upon their respective guide rails. As soon as the gripping jaws come into engagement with the guide rails, the resistance to thefurther movement of the wedges 44, 44, etc. immediately increases until it reaches an amount sufficient to overcome the frictional engagement existing between the cable 18 and the cable clamp 53 which limits the pressure exerted by the wedges. As soon as this point has been reached, the cable slips through the clamp 53 and continues to rotate the drum, the clamp 53 traveling in the slot 51 as the cable unwinds. The screws 37, 37 driven by the drum through the spline 27 will continue to rotate in the nuts 38, 38 and move bodily outwardly, thereby forcing the wedges 31, 31 between the rollers 34, 34 and causing thegripping aws to clamp the guide rails with great power. In this manner the moving elevator car is quickly and smoothly brought to rest.

In order to reset the safety device after the same has operated, a bar may be inserted in the holes 66 in the periphery of the safety drum- 23, and the latter, together with the screws 37, 37, will be rotated backward. In this manner the gripping jaws will release their hold upon the guide rails, 13o

and the wedges 44, 46, etc., will be pulled back into normal position by reason of the frictional engagement existing between the wedges and the cable 18 at the clamp 53. The yielding connection 17 is again placed in normal position and the safety device is once more restored to normal conditions. WVhen the safety device operates with an upwardly moving car, a portion of the cable 67 will be unwound from the drum 64, while with a downwardly moving car the cable 67 will be slacked. In the first instance it would be necessary when resetting the safety again to wind the cable 67 upon the drum, while in the second instance the slack in this cable will be automatically taken up.

Referring to the modification shown in Figs. 8 and 9, 72, 72 designate a pair of similar clamping members or dogs which are secured upon shafts 74, 74, arranged to rotate in bearings 73, 73 carried by the frame 50. Upon each end of the shafts 74, 74 are secured lever arms, such as 76, 7 6, and between adjacent lever arms is a tension spring 77 so arranged that its tension may be readily adjusted to any-desired degree. Between the dogs 72, 72 is located the cable 18, to which is rigidly attached a cable bob 53. This bob 53 when in normal position is located just below the dogs 72, 72 and in contact therewith. Fixed stops 79, 79 are arranged upon the bearings 7 3, 73 which cooperate with corresponding detents 79, 79 whose function is to limit the movement of the dogs 72, 72 toward each other effected by the action of the springs 77, 77. The operation of this device is as follows: As soon as the safety device is set into opera tion, motion is imparted to the cable 18 and bob 53 affixed thereto, and the latter tends to force apart or rotate the dogs 72, 72.

Since the dogs are spring pressed, in order to pull the bob through the dogs against the action of the springs a certain resistance must be overcome, and the magnitude of this resistance is determined largely by the amount of tension in the springs. It is readily seen that as the bob moves upwardly (Fig. 9) it carries with it the dogs 72, 72, together with the frame 50 and connected wedges 44, 46, etc. In this manner the wedges operate to quickly take up all lost motion and backlash in the safety device mechanism and to set the clamping jaws upon the guide rails as before pointed out.

As soon as the wedges meet with a certain resistance to their further movement, the dogs 72, 72 connected thereto are forcibly opened by the bob 53 as the latter continues to move upwardly. As soon as the bob has moved out of engagement with the dogs 7 2, 72 the latter are moved back into original position against the stops 7 9, 7 9 by means of the springs 77. It is readily seen that as soon as the bob has been pulled through the dogs and the latter have returned to original posit-ion, the cable 18 is no longer retarded in its movement by the dogs and their connected parts, and the tension in the same is reduced to an amount just sufficient to continue to rotate the drum on the safety device. In this manner the strain upon the cable 18, as well as that upon the governor cable 12, is reduced to a minimum. It will be noticed upon an inspection of Fig. 9 that the bob 53 is tapered at either end, the taper at the upper end being considerably less than that at the bottom. The taper at the top of the bob, together with the inclination of the lower surfaces of the dogs and the tension of the springs 77, 77, determines the amount of frictional engagement existing between the cable 18 and the dogs, and by varying any one of these cooperating elements, such as the tension of the springs 77 77 the upward pull upon the wedges may be regulated to any desired amount. The taper upon the bottom of the bob is gradual so that when resetting the safety device by hand the bob will readily force the dogs apart and come to its original position with minimum effort upon the part of the operator. Whereas it is only necessary to employ a single spring 77 to actuate the dogs 72, 72, I prefer to use two springs so that in case one should become broken the device would still be effective.

In safety devices of this general character it is customary to cause the gripping jaws first to move quickly into position against the lateral faces of the guide rails by means of springs, cams, high pitch screws, or similar devices, after which a low pitch screw is called into operation to gradually tighten the jaws upon the rails. Such methods are open to the objection that they all operate on similar principles; that is, they require two mechanisms for operating the gripping jaws, one mechanism being arranged to first move the jaws int-o engaging position on the rails with a certain pressure, after which the other mechanism is called into operation to further tighten the aws upon the rails until the car finally comes to rest. The operation of each of these mechanisms may be independent of each other or not, as the case may be; in either case the failure of one to operate at the proper time will seriously affect the operation of the safety device as a whole. In a safety device embodying my invention, the quick acting means for bringing the gripping aws into engagament with the guide rails, and the slower and more powerful means for tightening the aws upon the rails, are set into operation simultaneously the moment the governor grips the governor cable, and the safety drum 23 starts to rotate. Since the cable 18 is unwound from the drum 23 at the same speed that the elevator car is moving, the wedges 44, 46, etc.,

will be pulled upwardly (Figs. 2 and 3) by means of the friction connect-ion between said cable and the clamp 53 in a very short space of time, depending upon the pitch of the inclined faces of the wedges. This pitch, as before stated, should not be too steep, for the reason that there would be danger of the wedges being forced backward against the opposing frictional pull of the cable clamp 53, as the thrust of the traveling nuts against these wedges will greatly increase as the rotating screws 37 37 force the gripping jaws against the rails with great power. Since the wedges 4A, 46, etc., are operated by reason of the friction existing bet-ween the cable 18 and clamp 53, and since this friction may be adjusted or regulated to any desired amount by means of the screws 55, the apparatus may be so adjusted that the wedges will merely bring the gripping jaws into position against the rails, or, if so desired, this friction may be increased so that the wedges will set the jaws with a certain predetermined pressure on the rails. As soon as the wedges have performed their function, the screws 37, 37 further increase this pressure until sufiicient friction exists between the rails and the gripping jaws to stop and hold the car against further movement. Since the simultaneous operation of the wedges 4A, 46, etc., and the screws 37, 37, in bringing the jaws into engagement with the rails takes place very quickly, the

pitch of the screws 37, 37' may be correspondingly low, and thus the strain upon the cable 18 will be comparatively small, while at the same time the jaws will be tightened upon the rails with sufficient power to stop the car before the same has acquired too much momentum.

The means for operating the safety de vice from the car comprises a cable drum 64 located upon the outside of the car, which contains a cable 67. This cable is wound about the drum a number of turns and has one end connected thereto. The other end of the cable leads up over suitable guide pulleys 68 and is connected at 61 to the governor cable 12 and cable 18. The drum 64 is rigidly connected to a toothed wheel 63 which is arranged to cooperate with a latch 70 carried upon the lever 60. This lever is preferably arranged in close proximity to the car operating lever 65 so as to be within convenient reach of the operator. The latch 7 0 is normally held out of engagement with the toothed wheel 63 by means of a spring 69 and the same may be placed into engagement with the toothed wheel by means of the hand lever 62. Under normal conditions the drum 6 1 is free to rotate; thus the manually operable means does not interfere in any way with the proper operation of the automatic means for applying the safety device. In order to operate the safety device from the car, the operator grasps the levers 60 and 62, and by so doing forces the latch 70 into engagement with the toothed wheel 68 and thus places the lever 60 into operative connection with the drum 64. Upon pulling the lever to the right, the drum 64: is rotated in a clock-wise direction, thereby winding up the cable 67. Since this cable is operatively connected to the cable 18, the latter is pulled through the pulleys 19, thereby effecting theoperation of the safety device as before described in connection with the automatic operation effected by the speed governor. The drum 6% may be rotated any desired amount by rocking the lever 60 back and forth, the latch 70 being disengaged from the toothed wheel 63 when the lever 60 is moved in a left-hand direction by relieving the pressure upon the leplies a simple and efficient apparatus for automatically stopping an elevator car whose speed has exceeded a certain predetermined limit in as short a space of time as is prac tical. The interval of time required to move the gripping jaws from normal position into a position against the guide rails being so short that for all practical purposes the operation is substantially instantaneous, a restraining influence is brought to bear upon the moving elevator car before the same has had time to move more than two or three inches. The act-ion of the right and leftscrews in further forcing the jaws upon the guide rails is much slower, with correspondingly greater power. In this manner the safety device promptly gets into action the moment the governor acts, and by the gradual application of increasing holding power produces a sure and gradual stop. I

While I have shown a preferred construction of my device, I desire not to be limited to the precise arrangement of parts herein disclosed, since it is obvious that those skilled in the art could readily make various changes in details of construction without departing from the spirit and scope of my invention.

What I claim as new and desire to have protected by Letters Patent of the United States is:

1. In an elevator safety device, the combination of a car, guides over which the car travels, clamping jaws carried by the car and arranged to engage the guides, means comprising wedges for quickly operating the clamping jaws, additional means for slowly operating said clamping jaws, and means for effecting the simultaneousaction of both of said operating means. W

2. In an elevator; safety device,fthecombination of a car, guide rails therefor, clamps carried by the car and adapted to engage said guide rails, frictional means for operating the clamps, positive means for operating the clamps, and means for effecting the simultaneous operation of both of said operating means.

3. In a safety device for elevators, the combination of guide rails, gripping members adapted to engage said guide rails, wedges for moving the gripping members quickly into operative position, screws for tightening said gripping members slowly upon the guide rails, means for eflecting a simultaneous operation of said wedges and screws, and for discontinuing the movement of said wedges when the gripping members meet with resistance.

4-. in a safety device for elevators, the combination of a car, guide rails therefor, clamps carried upon said car, a device for operating said clamps, wedges for effecting the operation of said device whereby said clamps will engage said guide rails with a predetermined pressure, and screws for further increasing this pressure.

5. In an elevator safety device, the combination of a car, guide rails therefor, a clamping device, friction operated means for actuating said clamping device positively operated means for actuating said clamping device, and means operative upon excessive car speed for simultaneously efiecting the operation of both of said clamp actuating means.

6. The combination with an elevator car, of a clamping device comprising gripping jaws, right and left threaded screws associated with said jaws, means for rotating both screws, a nut threaded upon each of the screws, wedges arranged bodily to move each nut, and means for effecting a simultaneous movement of said wedges and a ro tat-ion of said screws.

7. The combination with an elevator car,

of a clamping device therefor, right and left screws associated with said clamping device, a nut threaded upon each of said screws, wedges arranged bodily to move each nut, a governor, and means associated with said governor for effecting simultaneously a movement of the wedges and a rotation of said screws.

8. The combination with an elevator car,

of a clamping device therefor, right and left screws associated with said clamping device, nuts threaded upon each of the screws, wedges co-acting with said nuts, means for simultaneously effecting a longitudinal and rotary motion to said screws, and means for limiting said longitudinal movement when the clamping device meets with resistance.

9. In an elevator safety device, the combination of a car, a clamping device carried by said car, frictional means for operating said clamping device, positive means for operating said clamping device, and independent automatic and manual means for effect ing the simultaneous operation of both of W. H. BRADY, Erma L. Aus'rnnn.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

' Washington, 1). 0.

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