US323019A - Ceoft - Google Patents

Description

(No Mode i.) Y

J. S. BANOROFT.

MACHINERY FOR TRANSMITTING MOTION. No. 323,019. Patented July 28,1885.

Fig.

Witnesses: Inventor: W 9- WW fi UNITED STATES JOHN SELLERS BANCROFT, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO \VILLIAM SELLERS, OF SAME PLACE.

MACHINERY FOR TRANSMITTING MOTION.

SPECIFICATION forming part of Letters Patent No. 323,019, dated July 28, 1885.

Application filed June 15, 1885.

To all whom it may concern:

Be it known that I, Joi-iN SELLERs BAN- CROFT, of the city and county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Machinery for Transmitting Motion and Preventing Reaction, of which improvements the following is a specification.

The importance of providing devicesin all machinery which is intermittent in its action, and in which the work or load tends to react, whereby the load will be prevented from reacting through the driving-gear and revers ing the motion of the machinery, with its usual disastrous results, has long been known, and a variety of devices have been employed for this purpose, and as hoisting machinery is always improved by such appliances, I have chosen this form of machine to illustrate my invention, and my subsequent description will have reference to this form only. Such appliances have either been defective in their action or difficult of adjustment, for most of them have to be thrown into gear by the operator in order to retain the load, or adjusted by him in order to lower, and in either case carelessness on his part may result in serious accidents, and those devices which have been made automatic in their action have the serious defect either that it is exceedingly difficult to make the necessary adjustments for wear, or that they frequently permit a considerable reaction of the driving-machinery before the retaining-pawl employed comes into action, and the consequent sudden stop of the machinery under the strain of the load involves destructive shocks on the machinery and load.

It is an object of my present invention to provide a retaining device which shall be entirely automatic in its action, and so arranged as to hold the load at any point, while permitting free transmission of motion through it from the power to the load.

It is a further object of-my invention to reduce the shocks upon the load and the transmitting machinery by reducing the reactionary motion within the least possible limits; and to these ends my invention consists in a (No model.)

friction-clutch so arranged as to be continu- 5o ally tightened by the pressure of the load and capable of being released by the driving-power, operating in conjunction with a self-tightening brake, which permits mot-ion in one direction and prevents motion in the opposite 5 5 direction.

In the accompanying drawings, which form part of this specification, Figure 1 represents a plan of a hoisting-machine, showing an application of my present invention. Fig. 2 is a sectional view of Fig. 1 on the line 2 2. Fig.

3 is a side elevation, partly in section, of Fig. 1.

A is the hoistingdruin, to which is secured the rope or chain a, carrying the weight to be raised TV. The drum A is firmly secured to a shaft, B, so as always to turn with it. This shaft B is journaled in bearings (J O, secured to a frame.

The driving-gear D is provided with a screwthread in its hub, which engages with a similar thread formed upon the shaft B, so that any rotation of the gear D relatively to the shaft will screw it along the shaft, so as to clamp the retaining-collar G between the gearwheel D and the friction-clutch E, or release it, according to the direction in which it may be turned.

The friction-clutch E is secured to the shaft B by a key, as shown in Fig. 2, so as to revolve with the shaft, and it is possible to adjust it along the shaft by means of the nut F. Between the gear-wheel D and friction-collar E, fitting loosely 011 the shaft, is the retainingcollar G, on the periphery of which is placed a brake-band, H, preferably lined with wood, leather, or some equivalent material havinga high coefficient of friction, for the higher the coeflicient the greater can be the proportional distance between the points of attachment 1) and f of the levers-J J, presently described, the less will be the strain on the strap H, and the less the reaction will be, while such material also serves to diminish the risk of abrasion or cutting between the brake-band H and the retaining-collar G. The upper end of the brake-band H is connected by a bolt, b, to the levers J J, the outer ends of the levers being united by the bolt 9, which is supported by the stand K, secured to the frame which carries the machine. This stand K is slotted, as shown in Figs. 1 and 3, so as to allow the outer ends of the levers J Jto move in and out from the shaft B without permitting any rotation about the axis of the shaft, The lower end of the brake-band H is attached by abolt, c, and swivel-block L to the lovers J J, the nuts (I and e on the bolt 0 serving to adjust the position of the levers J J and the grip of the brake'band H on the collar G.

It will be observed in Fig. 3 that if the retaining-collar G is revolved in the direction of the arrow the tendency would be to release the pressure of the brakeband H in carrying it around with the collar G, for the outer end of the levers J being held at a uniform height by the stand K, the raising of the inner end of the levers J J by the rotation of the band H will raise the bolt b faster than the trunnions f of the swivelblock L, to which the lower end of the brake-band is attached, on account of the difference in their respective distances from the stand K, and consequently the pressure of the brakeband H upon the retainingcollar G will be released as the inner ends of the levers J J are raised. On the contrary, when the collar G is turned in an opposite direction to that indicated by the arrow thefriction of the brakeband, supplemented by the weight of the levers J J and swivelblook L and connections, will cause the inner ends of the levers J J to fall, and consequently toincrease the grip of the brake-band H on the retainingcollar G. and by properly proportioning the relation between the two arms I) f and f of the levers J J the brake-band may be made to hold the collar G with any desired pressure, so as to effectually prevent any sliding or reaction of the collar G under the brake in this direction; and if the brake-band H is made to accurately fit the outside of the retainingcollar G a very minute angle of rotation will be sufficient to apply or release the brake, as the case may be. This angle of rotation measures the reaction or drop of the load when the hoisting power is withdrawn, and it will be ob served that the'amount of reaction will be very much less than would be at all possible with a ratchet-wheel and pawl of suflicient strength and surface to hold the load, and also that the arrest or stop of the load will be less of a blow or shock, even with the same amount of reaction, on account of the elasticity of thelevers and gradual tightening of the brakestrap.

The operation of the device is as follows: The gear D is driven in the direction of the arrow in Fig. 3 by the pinion M. This causes the wheel D to revolve around the shaft as a nut turns on a bolt, pushing the retainingcollar G along the shaft until it is resisted by the friction-clutch E and pressed against it with suflicientforce to turn the shaft B and through it the drum carrying the load.

will be observed that the power appliedtto turn the gear-wheel D, and the resistance of the drum A due to the weight of the load, tend to screw the gear-wheel along the shaft, so as to increase the pressure between the surfaces of the friction-clutch E, retainingcollar G, gear-wheel D, and the screwethread 011 the shaft until the work of lifting the load is balancedby the resistance to turning the gear-wheel on its shaft. All of these pieces now revolve as one solid mass, the frictionbrake H being released by the lifting'of the levers J J, as already described, so as to allow the retaining-collar G to turn freely with the least resistance. If, now, the driving power be withdrawn, the weight W will tend to revolve the whole mass in a direction opposite to that indicated by the arrow, and the brake H will immediately, by the lowering of the levers J J, as before described, firmly grasp the retaining-collar G and stop its rotation, and the weight WV will be securely held, for any effort of the weight to turn the drum must evidently tend to screw the parts still more firmly together, which is impossible, as they have already, by the action of the hoisting-gear, been locked together wit-h force sufficient to lift the weight. If it be desired to lower the weight, the gear-wheel D is turned in the opposite direction by means of the pinion M. This releases the pressure with which the friction-clutch E is held into the retaining-collar G until the weight W is able to turn the drum. If, now, the weight tends to turn the drum any faster than the gearwheel revolves, such action immediately reclamps the clutch E to the retaining-collar G, and the load is held until the revolution of the wheel G again. releases it, so that the weight cannot lower any faster than the rate of revolution of the driven gear-wheel D.

In order that the operation of lowering may be made with a small expenditure of power, the frictional surface of the clutch E. should be of greater diameter and offer much more resistance to rotation than the frictional surfaces between the gear-wheel D and the -re taining-collar G.

Resistance to the turning effect due to the reaction of the weight is, measured by the pressure on the friction-surface between the clutch E and the collar G, and the larger this is in diameter the less will be the pressure with which the gear-wheel D will be forced against the retaining-collar G by the rotation of the drum, and consequently the less will be the force required to unscrew thewheel D for the purpose of lowering.

I prefer to make one of the pair of frictional surfaces in each case of wood or leather, or some equivalent material, to avoid cutting and obtain smooth action of the device.

I do not limit myself to the screw-connection shown between the gear-wheel and shaft, for it will be evident that the same results would be obtained by suitable cams on the ends of the hubs of the gear-wheel and drum.

Having now described my invention, what opposite direction, the combination being and I claim as new, and desire to secure by Letters operating substantially as and for the purposes 10 Patent, isset forth. v

In machinery for transmitting motion and preventing reaction, a friction-clutch which SELLERS BANOROFT' is engaged by the reaction of the load, in (30111- \Vitnesses: bination with a brake which permits motion COLEMAN SELLERS, J 1

in one direction and prevents motion in the CHAS. M. MILLER.

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