US3250348A - Overspeed brake for elevator cage - Google Patents

Description

May 10, 1966 o. E. MOYER OVERSPEED BRAKE FOR ELEVATOR CAGE 5 Sheets-Sheet 2 Filed July 7, 1964 ATTOQNEVS 0. E. MOYER OVERSPEED BRAKE FOR ELEVATOR GAGE May 10, 1966 5 Sheets-Sheet 5 Filed July 7, 1964 w vmwww .R WM an M fiw lmv M 5 08 May 10, 1966 MOYER 3,250,348

' OVERSPEED BRAKE FOR ELEVATOR CAGE Filed July '7, 1964 5 Sheets-Sheet 4- A TTOPNEVS May 10, 1966 o. E. MOYER OVERSPEED BRAKE FOR ELEVATOR CAGE 5 Sheets-Sheet 5 Filed July 7, 1964 /A/VENT01Q ATTORNEYS.

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United States Patent 3,250,348 OVERSPEED BRAKE FOR ELEVATOR CAGE Oscar E. Moyer, Zelienople, Pa., assignor to Universal Manufacturing Corporation, Zclienople, Pa., a corporation of Pennsylvania Filed July 7, 1964, Ser. No. 380,763 4 Claims. (Cl. 188-188) This invention relates to elevators, and more particularly to brakes for automatically stopping elevators in case they start to fall or otherwise move too fast.

Elevators are often provided with brakes for stopping them automatically in emergencies, but such brakes generally operate only in case the cable that supports the elevator breaks, which would allow the elevator to fall. There are occasions, however, where it may be desirable to stop an elevator because it has started to move too fast and may get out of control. This is especially true of material handling elevators used at building sites, which are operated by a man at a winch onthe ground. If he misjudges'the speed of the elevator or otherwise lets the elevator run away, it may strike the ground before he can stop it. One way of solving the problem is disclosed in my patent 2,945,561. The overspeed brake disclosed therein performs its function satisfactorily, but it is more complicated and expensive than generally desired, and it is rather difiicult to attach to existing elevator installations.

It is among the objects of this invention to provide an elevator brake, which will automatically stop the elevator if it starts to exceed a predetermined speed even if the supporting cable has not broken, which is relatively simple and inexpensive in construction, and which can easily be attached to an existing elevator cage in the field.

In accordance with this invention a brake housing is provided that can be attached to an elevator cage that travels between vertical guide rails. Rollers are carried by the housing for rolling along the rails. Movable means in the housing urge brake shoes toward rail-engaging position, but a trigger also mounted in the housing normally holds the movable means in shoe-retracted posi- A rotatable governor member is mounted in the housing adjacent the trigger and is driven by the rollers. Whenever the rollers reach a predetermined maximum speed a normally retracted trigger releaser, which is movably connected to the rotatable governor member, is moved outwardly by centrifugal force far enough to strike the trigger in order to release it from the movable means so that the latter can move the shoes to railengaging position.

The preferred embodiment of the invention is illustrated in the accompanying drawings, in which FIG. 1 is a front view of an elevator suspended in the lower end of a tower;

FIG. 2 is a fragmentary side view of the elevator and tower;

FIG. 3 is an enlarged horizontal section of the brake, with portions broken away;

FIG. 4 is a front view of the brake shown in FIG. 3;

FIG. 5 is an enlarged end view of the brake at the end opposite to the one shown in FIG. 2; and

FIGS. 6, 7 and 8 are enlarged vertical sections of the brake taken on the lines VIVI, VIIVII and VIII- VHI, respectively, of FIG. 4.

Referring to FIGS. 1 and 2 of the drawings, an elevator cage 1, such as used for carrying building materials at a construction site, may be suspended in a portable tower 2 by one or more cables 3 connected by a hitch 4 at the center of the top of the cage. The cable extends up over sheaves (not show) at the top of the tower and then down to a winch on the ground beside the 3,250,348 Patented May 10, 1966 'ice tower. An operator, standing beside the winch, controls the ascent and descent of the elevator cage in the tower. The cage is guided by vertical rails 5 rigidly secured to the inside of the tower centrally of two opposite sides.

A rectangular frame or brake housing 8 is provided, the length of which corresponds to the width of the elevator cage. Secured to the end walls of the housing are upwardly projecting face plates 9 that are bolted to the opposite sides of the lower part of the cage in positions to suspend the housing directly beneath the floor of the cage. Also, as shown in FIGS. 2 and 5, at each end of the housing a pair of grooved rollers 10 and 11 engages opposite sides of the adjoining guide rail 5 in order to rotate as the cage is raised and lowered. As shown in FIGS. 3 and 4, axially aligned rollers 10 are rigidly mounted on the opposite ends of a shaft 12 that is journaled in bearings 13 secured to the ends of the housing and also in bearings 14 secured to a pair of spaced vertical plates 15 rigidly mounted in the central portion ofthe housing.

The other pair of rollers is rigidly mounted on the opposite ends of a shaft 18 (FIG. 3) parallel to the first shaft. This second shaft extends through enlarged openings 19 (FIG. 5) in the ends of the housing and is journaled in bearings 20 mounted on upright brackets 21, the lower ends of which are pivotally connected by bolts 22 to cross bars 23 in the bottom of the housing as shown in FIG. 6. Shaft 18 is urged toward the other shaft by means of coil springs 25, each of which is compressed between the upper end of one of the brackets and a horizontal bar 26 at one side of the housing. The central portion of the shaft likewise is journaled in bearings 27 mounted on the upper ends of small plates 28 that are pivoted by bolts 29 to cross bars 30 in the bottom of the housing near the central plates 15 as shown in FIG. 7. Rollers 11 are pressed against the guide rails 5 by springs 25 and thereby hold the other pair of rollers against the rails also. The two shafts are geared together by a pair of gears 31 rigidly mounted on them so that all of the rollers and both shafts must turn in unison at all times while the cage is in motion, even if the rollers on either shaft happened to slip on the rails.

Secured to the outside of each end of the housing above roller 10 is a stationary brake shoe 33 (FIGS 2 and 5) having a concave surface that slides along the adjacent side of one of the guide rails. Opposing each of these shoes on the opposite side of the adjoining rail is a movable barke shoe 34, also provided with a concave rail-receiving surface at its inner end. The outer ends of the two movable shoes are mounted on the opposite ends of movable means, by which they are urged toward rail-engaging position. This movable means includes a pivotally mounted frame which preferably is T-shape and formed from a shaft 35 (FIGS. 3 and 4) and a central arm 36 (FIG. 8) projecting radially from it between vertical plates 15. The opposite ends of this frame shaft are journaled in bearings 38 secured to the opposite ends of the housing, while the central portion of the shaft extends through a pair of bearings 39 mounted on the central vertical plates. The movable brake shoes are rigidly mounted on the projecting ends of the shaft. The arm 36 may be formed from a pair of spaced parallel bars 40 welded at one end to a sleeve 41 keyed on shaft 35, and connected at their opposite ends by a croses bar 42. The central portions of the side bars have between them an inverted U-shape bracket 43 that is pivotally connected to the bars by bolts 44. The lower surface of the top of this bracket is engaged by the upper end of a coil spring 45, the lower end of which is seated on another U-shape bracket 46 pivotally supported by central plates 15. The spring urges the arm upwardly into the upper of two positions, in which the inner ends of the movable brake shoes are swung upward into tight engagement with the adjoining guide rails.

Since the brakes are to be applied to the rails only in emergencies, which it is hoped will never arise, they are normally held retracted by means of a trigger 48 that maintains the frame arm 36 in its lower position shown in FIG. 8, with the brake shoes released. Preferably, this trigger is formed from a U-shape member 49 pivotally suspended from a horizontal pin 50, the ends of which are mounted in brackets 51 welded to the central vertical plates. The central portion of the U-shape member carries a plate 52 that engages the top of cross bar 42 at the outer end of arm 36 in order to hold the arm depressed against the resistance of spring 45. The trigger normally is held in this operative position by means of a small coil spring 53 compressed between it and a side bar 54 of the brake housing. As long as the trigger holds the arm depressed, the pivoted brake shoes are free of the guide rails.

If the cage begins to descend faster than a predetermined speed considered to be safe, trigger 48 will be released from arm 36, whereupon coil spring 45 will raise the arm and apply the brakes. To release the trigger under such an overspeed condition, a governor is provided that is operated by the rollers. Another feature of this invention is that the governor includes a rotatable member or governor disc 56 rigidly mounted on the center of roller shaft 12 beneath the trigger and the outer end of the arm, as shown in FIGS. 4 and 8. This dis-c carries a normally retracted trigger releaser which, when the rollers reach a predetermined maximum speed, is moved outwardly by centrifugal force far enough to strike the trigger to release it from the arm. The trigger releaser includes at least one lever 57 that is pivotally connected to one side of the disc on a pin 58 and that normally is held in a retracted position against a stop 59 by means of a coil spring 60 connecting it to an adjusting screw 61 attached to a lug 62 on the disc. Preferably, the outer end of the lever is made heavy by welding weights 63 to its opposite sides. In the retraction position of the lever the disc can rotate without the outer end of the lever engaging the lower end of the trigger, which extends across the disc. However, as the speed of the disc increases, a point can be reached where centrifugal force will overcome the resistance of spring 60 and swing the outer end of the lever outward beyond the edge of the disc far enough for it to strike the bottom of the trigger and knock it away with arm 36 so that trigger plate 52 will be withdrawn from the arm to allow the arm to be pushed upward by the spring beneath it. The rotational speed of disc 56 that must be reached before the trigger will be released can be controlled by adjusting the tension on spring 60.

To reduce by one-half the distance that the governor discs 56 has to turn before the trigger will be struck by the trigger releaser, it is preferred to provide the disc with a second lever 65 pivotally connected to the disc on a pin 66 diametrically opposite to pivot pin 58. The two levers extend in opposite directions from the two pins. To make certain that lever 65 will swing outward at exactly the same time as the other lever, it is not re strained by a separate spring but is connected to lever 57 by a link 67 that is pivoted to both of them. One end of the link is attached to lever 65 between its outer end and and its pivoted inner end, but the opposite end of the link is connected to an inner end portion of the other lever that extends beyond pivot pin 58.

As a further precaution against failure of the governer to operate, and also to help balance it, it is desirable that another pair of identical levers be mounted in the same way on the opposite side of the disc. However, the second pair are reversed relative to the first pair. That is, the connecting link 67 for one pair of levers is at one side of the shaft 12, while the corresponding link for the other pair of levers is at the opposite side of the shaft. This means that each long lever will be directly opposite the short lever on the other side of the disc.

During ordinary use of the elevator, the rollers run up and down the guide rails without operating the governor fast enough to cause it to release the trigger from the spring-pressed arm 36. If for any reason the elevator cage starts to descend faster than the safe speed for which the governor is set, the levers on the governor disc will swing out and knock the trigger away from the arm. Immediately, the arm will ,be swung upward by spring 45 and that will rotate the shaft 35 on which the brake shoes are mounted, so the inner ends of the shoes will be swung up tightly against the rails. No matter how much pressure is exerted by the pivoted shoes, the guide rails will not bend because they are backed up by the stationary guide shoes 33 on the opposite side.

In order to release the brakes after they have been applied, a lever 70, shown in FIG. 2, that is rigidly connected to one end of brake shaft 35 and that is swung downward when the brakes are applied, is raised manually to turn the shaft and thereby swing arm 36 downward until the trigger snaps into place over its outer end to hold the arm depressed. The braking mechanism then is ready for operation again in case the cage travels too fast. Lever 70 may be operated by extending its outer end and through a stirrup 71,the upper end of which is pivotally connected to a longer horizontal lever 72 that in turn is pivotally connected at the same end to a bracket 73 on the bottom part of the elevator cage. When the free end of this upper lever, which lies on the cage floor, is raised it will lift the stirrup and thereby swing the lower lever 70 upwardly. On the other hand, when the upper lever is down in its inactive position, the lower lever is free to swing downward in the stirrup in case shaft 35 turns to apply the brakes.

It will be seen that this brake will do everything that the one covered by my earlier patent accomplished, but the new one is less expensive and has the great advantage that it can be sold as a unit for quick attachment to elevator cages already in use.

I claim:

1. An overspeed brake for an elevator cage travelling between vertical guide rails, the brake comprising a housing adapted to be fastened to such a cage, rollers carried by the housing for rolling along the guide rails, brake shoes, movable means in the housing urging the shoes toward rail-engaging position, said means including a pivotally mounted frame extending across said housing and having a radially projecting arm, a spring connected with the arm and urging it in one direction, a trigger movably mounted in the housing and engageable with said arm to arrest its movement in said direction for normally holding said frame in shoe-retracted position, a rotatable governor member mounted in the housing adjacent said trigger and driven by said rollers, and a normally retracted trigger releaser movably connected to the rotatable member and adapted when the rollers reach a predetermined maximum speed to be moved outwardly by centrifugal force far enough to strike the trigger to release it from said arm, whereupon said frame can move the shoes to rail-engaging position.

2. An overspeed brake according to claim 1, in which said frame is T-shape and includes a shaft pivotally mounted in the housing and supporting the brake shoes on its ends, and said arm projects radially from the center of the shaft.

3. An overspeed brake according to claim 2, including a lever rigidly connected at one end to said frame shaft and projecting laterally therefrom in a direction to swing downward when the brake shoes are applied, and means for manually lifting the other end of the lever to rotate said shaft in a direction to release the brake shoes.

4. An overspeed brake for an elevator cage travelling between vertical guide rails, the brake comprising a housing adapted to be fastened to such a cage, rollers carried by the housing for rolling along the guide rails, there being a pair of said rollers engaging opposite sides of each rail, means gearing the rollers in each pair together, brake shoes, movable means in the housing urging the shoes toward railengaging position, a trigger movably mounted in the housing and normally holding said means in shoeretracted position, a rotatable governor disc mounted in the housing adjacent said trigger and driven by said rollers, a pair of levers, means pivotally supporting said levers on said disc on diametrically opposite sides of its center, said levers being long enough to extend beyond the outer edge of the disc and strike the trigger, and resilient means 1 normally holding the outer ends of the levers retracted References Cited by the Examiner UNITED STATES PATENTS 1,165,583 12/1915 Farmer 188-188 1,298,066 3/ 1919 Lindquist 187--89 1,995,274 4/1933 Dunlop 188-188 2,244,893 6/1941 Panter 188l88 2,931,466 4/ 1960 Allenbaugh 188l8 8 DUANE A. REGER, Primary Examiner.

Claims (1)

1. 4. AN OVERSPEED BRAKE FOR AN ELEVATOR CAGE TRAVELLING BETWEEN VERTICAL GUIDE RAILS, THE BRAKE COMPRISING A HOUSING ADAPTED TO BE FASTENED TO SUCH A CAGE ROLLERS CARRIED BY THE HOUSING FOR ROLLING ALONG GUIDE RAILS, THERE BEING A PAIR OF SAID ROLLERS ENGAGING OPPOSITE SIDES OF EACH RAIL, MEANS GEARING THE ROLLERS IN EACH PAIR TOGETHER, BRAKE SHOES, MOVABLE MEANS IN THE HOUSING URGING THE SHOES TOWARD RAIL-ENGAGING POSITION, A TRIGER MOVABLY MOUNTED IN THE HOUSING AND NORMALLY OF HOLDING SAID MEANS IN SHOERETRACTED POSITION, A ROTATABLY GOVERNOR DISC MOUNTED IN THE HOUSING ADJACENT SAID TRIGGER AND DRIVEN BY SAID ROLLERS, A PAIR OF LEVERS, MEANS PIVOTALLY SUPPORTING SAID LEVERS ON SAID DISC ON DIAMETRICALLY OPPPOSITE SIDES OF ITS CENTER, SAID LEVERS BEING LONG ENOUGH TO EXTEND BEYOND THE OUTER EDGE OF THE DISC AND STRIKE THE TRIGGER, AND RESILIENT MEANS NORMALLY HOLDING THE OUTER ENDS OF THE LEVERS RETRACTED BUT ADAPTED TO PERMIT THEM TO SWING OUTWARDLY BY CENTRIFUGAL FORCE TO RELEASE THE TRIGGER FROM SAID MOVABLE MEANS IF THE ROLLERS ATTAIN A PREDETERMINED MAXIMUM SPEED, WHEREUPON SAID MOVABLE MEANS CAN MOVE THE SHOES TO RAIL-ENGAGING POSITION.

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