US1769849A - Operating means for brakes - Google Patents

Description

July 1, 1930. H. w. c. LIDDIARD 1,769,849

OPERATING MEANS FOR BRAKES Filed July 11, 1927 2 Sheets-Sheet 1 Fig. I.

Inventor"- Hugh \A/ C. Liddiard,

- His Attorney y 1930. H. w. c. LIDDIARD I 3" OPERATING MEANS FOR BRAKES Filed July 11, 1927 2 sums-sum 2 Fig. 2.-

Fig. 3.

Inventor: Hugh W C. Liddiar'd,

His Attorney Patented July 1, 1930 UNITED STATES PATENT OFFICE HUGH W. C. LIDDIARD, OF RUGBY, ENGLAND, ASSIGNOR TO GENERAL ELECTRIC Q COMPANY, A CORPORATION OF NEW YORK OPERATING MEANS FOR BRAKES Application filed July 11, 1927, Serial No. 204,785, and in Great Britain August 4, 1928.

This invention relates to operating mechanisms, and particularly to such as are remotely controlled, and whilst it is not limited in this respect, the operating mechanisms,

according to the invention, are primarily applicable for remotely controlling, by electrical means, the braking devices of winders, cranes, lifts, and the like. The invention has for its object an improved arrangement by which the braking effort can be controlled from a distance, and applied gradually to any desired extent.

Operating mechanism, acording to the invention, comprises a pivoted lever, connected at one point to the means to be operated, and

at another point to biasing means (for instance, a weight or a spring), and means for moving one of these connection points along the levers, or for changing the point about which the lever pivots, in order to vary the effect of the bias on the means to be operated.

According to another aspect of the inven tion, the operating mechanism comprises a 2 pivoted lever, means applying a bias to a point on the lever, and means mounted on the lever for moving the point of application along the lever.

Preferably, the point of application which so is to be moved with respect to the lever is electrically controlled, as by means of a relay, or a plurality of relays, or by means of an electric motor; the arrangement being such that (for instance, in the case of an electric motor) the rotation of the motor in one direction moves the point of application away from the pivoting point and in the other direction towards the pivoting point.

In a preferred arrangement, according to 4 the invention, the bias is applied to the piv oted lever by means of a weight slidable along the lever.

More specifically, a brake-controlling mechanism, according to the invention, comprises a pivoted lever connected to operate the brake, an electric motor fixedly, and a weight slidingly, mounted on the lever on opposite sides of the pivot therefor, means for balancing the lever when the weight is in a predetermined position and the brake oil, a

coupling between the motor and weight whereby the weight can be slid along the lever in either direction according as to the direction of rotation of the motor, and means for controlling the energization of the motor so as to effect the rotation thereof in a particular direction.

With the arrangements above described, in which the point of application is electrically moved along the ivoted lever, additional means are prefera ly provided when a brake is being controlled, for applying the brake in the event of the failure of the electric supply. A further necessary feature is the provision of an automatically-operated c5 limit-switch, which is arranged to deenergize the electricmeans when the bias is applied to a predetermined point of the pivoted lever. Furthermore, if the machine which is being controlled by the brake is-itself electrically operated, it is advisable to provide means for automatically opening its circuit when the brake is applied inconsequence of supply-failure as aforesaid.

An arrangement, according to the inven- .55 tion, will now be described, by way of example, in connection with the diagrammatic representation of Fig. 1 of the accompanying drawing, in which Fig. 2 illustrates di agrammatically one method of controlling 1.1., the electric motor shown in Fig. 1, and Fig.

3 shows a modification of the arrangement illustrated by Figs. 1 and 2.

Referring to the drawings, wherein like reference numerals are used, as far as pos- 3-, sible, to denote similar parts, and particularly to Fig. 1, there is shown a rotatable brake wheel or drum 11, having externallycontracting brakeshoes 12 operating against its periphery, the brake-shoes being applied '15 to produce a braking effort through the system of lovers 13 when the rod 1 1 is pulled downwardly. The brake shoes are released in any suitable manner. The rod 14 is connected at its lower end at 15 to the lever 16, shown pivoted at 17. Mounted on the pivoted lever 16 is an electric motor 18, connected by gearing 19 with the rotatable screw 21 carried in bearings 22 on the pivoted lever 16. This screw is adapted to engage with a nut in the weight 23, which is slidable along the pivoted lever 16 in either direction according as to the direction of rotation of the screw 21.

Fig. 2 shows one simple arrangement for controlling the motor, which comprises a single two-position control switch 2 1- having two operating positions through which either of the contactor coils 25 can be closed. The contactor coils control contactor switches 28 respectively, and it will be noted that the connections of the motor 18 from the mains 27 through the two sets of contactor switches 26 are of opposite sense. Consequently, movement of the control switch 24 to the right will energize the right-hand contactor coil 25, and contactor switches 26 on the right-hand side, hus driving the motor 18 in one direction, say, for instance to move the weight 23 to the right (Fig. 1). Movement oi the control switch 2& to the left will effect the corresponding operation necessary to drive the weight to the left.

lVhen the weight 23 is moved to the right (that is, towards the pivoting point 17) to a predetermined position, it just balances the motor 18 and a counter-weight 28, arranged on an extended portion 29 of the pivoted lever, the braking el'lort of the shoes 12 being nil or a minimum inthis position of the weight 23. Movement of the weight 23 to the left increases the braking efi ort of the brake-shoes 12 to an extent depending on the position of the weight by tending to rotate the pivot-ed lever 16 counter clockwise and thus tending to pull down operating rod 1%. It will be seen that the pull exerted on the rod 14 by the weight 23 during the movement of the brake shoes 12 to their applied position varies from the minimum to the maximum value when the lever 16 rotates counter clockwise to the position shown in F ig. 1.

In order to prevent the over-running of the weight 23, limit-switches, indicated diagrammatically at 30, may be provided at both ends of the path of travel of the weight 23. These limit-switches preferably operate in the control circuits, as indicated in Fig. 2, though they may be arranged in other ways to effect the opening of the circuit for the motor 18.

In order that such a scheme shall be satisfactory in practice, it is essential to allow for cases in which the supply of power, either in the controlling circuits, or in the circuits of the electric motor, should rail. In order to deal with this situation, there is shown in Figs. 1 and 2 a brake-solenoid 31, which is energized from the mains 27, and which normally retains the pivoted bell-crank 32 with its end engaging the end of the catch 33. Suspended from the catch 33 is a weight 3%, and the catch 33 is also connected by means of the pivoted lever 35 with the pivoted lever 16, and therefore with the rod 14. In the event of a failure of supply in the mains 27, the brake-solenoid 31 becomes deenergized, and the bell-crank 32 rotating anti-clockwise disengages from the catch 33, allowing the weight 34: to apply the brake to the drum 11.

If the main machine with which the brake drum 11 is associated is adapted to be electrically driven, and is supplied from a source dili'erent from that for the motor 18, it is essential to ensure that, in the event of the brake being applied to the drum 11 due to failure of supply to the motor 18, the circuit for this main machine shall be opened. To provide for this, there is shown in Fig. 1 a t 'ipping device 36 operable by the falling of weight 34, which can be arranged in any suitable way as, for instance, by means of a relay) to effect the opening of the circuit for the main machine.

In Fig. 2 the brake-solenoid 31 is shown connected directly to the supply circuit 27. It the control circuits through control switch 2 1- were energized from a source difl'erent from 2?, it would obviously be necessary to eilect connections so that, in the event of failure of supply in the control circuit, the brake-solenoid 31 would operate in this case also. Furthermore, if a short-circuit or earth-fault should occur on the control circuits, the fuse or other protective device should be arranged so as to cut off power to the brake-solenoid 31 in order to trip the $511116.

In the diagrammatic modification illustrated by Fig. 3, means are provided for producing any degree of braking effort according to the position of the brake controller. The brake controller represented by 37 comprises a plurality of contacts 38, half of which are connected to the contacts 39, while the other half are connected to the contacts 41. Contacts 39 and 41 are arranged in two parallel lines on the pivoted lever 16, and slidable contacts i2 cooperating respectively therewith are adapted to be moved or oper ated by the weight 23, according to the position thereof. In circuit with the movable contacts 42 are the contactor coils 25 respectively and the limit switches 30. Attached to the handle of the braking controller is the movable contact member 43, which contacts with one less than half of the contacts 38 and is arranged according to its position to make certain of the contacts 3. and 41 alive through the associated contacts 38. If the weight 23,.

and consequently the slidable contacts 42, does not correspond to the position of the handle of the braking controller, then one of the sliding contacts 42 will be on a contact 39 or 41, as the case may be, which is alive, and the corresponding contactor coil 25 will be energized, thus setting the motor 18 in motion to move the weight 23, and the sliding contacts 42, in the appropriate direction that it may correspond in position to the position of the braking controller. As soon as this occurs the sliding contacts 42 will rest on seg- 'ments of the contacts 39 or 41, which are not alive, thus bringing the motor to rest. If the braking controller handle is then moved, one of the control circuits will be energized to cause the motor 18 again to move the weight 23 to a position that corresponds to that of the braking controller handle.

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

1. In a friction brake, a brake wheel, friction mechanism cooperating therewith,means including a system of levers for a plying said friction mechanism to said whee means associated with certain of the levers of said system for varying the application force of said friction mechanism, and additional means associated with certain of the levers of said system for applying said friction mechanism to said wheel.

2. In a friction brake, a brake wheel, friction shoes cooperating therewith, a system of levers for applying said shoes to said wheel, biasing means associated with certain of said levers for varying the application force of said shoes adjustable means cooperating with said biasing means for varying the biasing effect thereof, and means for applying the shoes independently of said biasing means.

3. In a friction brake, a brake wheel, friction shoes cooperating therewith, a system of. levers for applying said shoes to said wheel, a weight associated with certain of said levers for biasing the said shoes to the applied position, means for adjusting the position of said weight to vary the. effect thereof on said shoes, and biasing means associated with certain of said levers for biasing the said shoes to the applied position in case of failure of said adjusting means.

4. In a friction brake, a brake wheel, friction shoes cooperating therewith, means including a lever connected to said shoes for applying said shoes to said wheel, a weight mounted on said lever, an electric motor mounted on said lever for operating said Weight to and from the fulcrum of said lever to vary the effectiveness of the said Weight in applying a braking force to said wheel through said shoes, a second weight operably associated with said lever, means for suspending said weight, and means for releasing said Weight to apply the brake.

5. A brake-controlling mechanism comprising a pivoted lever connected to operate the brake, an electric motor fixedly and a weight slidingly mounted on the lever on opposite sides of the pivot therefor, means for balancing the lever when the weight is in a predetermined position and the brake off, a

! coupling between the motor and weight levers for. applying said shoes to said wheel,

a weight associated with certain of said levers for blasing the shoes to the applied position, means for adjusting the position of said weight to vary the effect thereof on said shoes, and preselective control means for arresting the adjustment of said weight in any one of a plurality of positions.

7. In a friction brake, a brake wheel, friction shoes cooperating therewith, a system of levers for applying said shoes to said wheel, 1

a weight associated with certain of said levers for biasing the shoes to the applied position, means for adjusting the position of said Weight to vary the effect thereof on said shoes, and pre-selective control means for .l

said adjusting means for arrestin the adj ustment of said weight in any one of a plurality of positions.

In witness whereof, I have hereunto set my hand this 21st day of June, 1927.

HUGH W. C. LIDDIARD.

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