US2140869A - Clutch - Google Patents

Description

R. T; WRIGHT Dec. 20, 1938.

CLUTCH Filed Feb. 4, 1957 2 Sheets-Sheet 1 Patented Dec. 20, 1938 UNITED STATES PATENT OFFICE oLU'rcn Robert '1'. Wright, Lake Biol, 111. Application February 4, 1937, Serial No. 124,101 8 Claims. (01. 192-41) This application is a continuation in part of application Serial No. 67,821, filed March 9, 1936.

The invention relates primarily to stencgraphic machines, particularly those which are 5 used for recording dictation in some form of code or phonetics, and the principal object of the invention is to provide a clutch mechanism for rotating the platen which operates on light pressure, has not lost motion or short travel, re-

10 turns instantaneously to its normal operating position, is noiseless, automatically adjusts itself to take up wear, is insensitive to dirt, rust, moisture and oil, and is simple in construction, positive in operation and inexpensive to manufacture.

15 Further and other objects and advantages will become apparent as the disclosure proceeds and the description is read in conjunction with the accompanying drawings in which Fig. 1 is a diagrammatic, perspective view of 20 the operating parts for the type bar and the clutch mechanism associated with the platen;

Fig. 2 is a perspective view of the clutch driver;

Fig. 3 is a perspective view of the clutch dog;

25 Fig. 4 is a sectional view of the clutch taken on the line 4-4 of Fig. 5;

Fig. 5 is a sectional view taken on the line 5--5 of Fig. 4, some parts, however, being shown in elevation for the sake of clarity;

30 Fig. 6 is a view corresponding to Fig. 4, but showing a modified form of the clutch in which gravity is relied upon to maintain the dog in engagement with the shaft prior to operation of the clutch.

35 The disclosure of preferred forms of the invention is in compliance with section 4888 of the revised statutes and should not be construed as imposing limitations on the appended claims unless required by the prior art.

40 Referring first to Fig. 1, in which the operating parts for the type bar and the clutch mechanism for rotating the platen are diagram matically shown, it will be seen that the platen I is journalled in the frame H of the machine,

3 and is adapted to receive the paper upon which the machine operates and moves it longitudinally prior to every operation of one or more keys l2. Neither the paper which receives the impression from the type bar, nor the plates for guiding the paper around the platen are shown, and reference is made to Ebelhare et al., Patent No. 1,264,909 for illustrating appropriate paper guiding means.

The keys I2 are mounted on key levers l3, pivoted at H to a fixed part oi the machine and having their resistance arms l engaging the power arms of bell crank levers l6, likewise pivoted, as at H, to a fixed part of the machine. The resistance arms of the bell crank levers l6 are connected as at l8 to type bars IS, the latter 5 resting upon the type bar support 20 and having suitable type 2| mounted on the face of the bar adjacent to the platen iii. A bank bar 22, usually adjustable in a vertical direction, limits the uppermost position of the keys l2 and a spring 23 10 attached to the power arm of each bell crank lever l6 maintains the key levers in constant en gagement with the bank bar 22.

Obviously, upon striking any one of the keys I2, the key lever l3 for that key rotates its associated bell crank lever to move the type bar I 9 toward the platen I0, and the downward movement of the key is limited by the meeting of the type 2| with the platen l0.

It is desirable to have finger pressure on the keys l2 rotate the platen Ill rather than use a spring for rotating the platen after finger pressure has been removed from the keys. The reason for this is that where springs are used for rotating the platen after the key has been struck, it is necessary for the finger pressure to be sufficient to extend the spring and the spring in turn must be strong enough to positively turn the platen after key pressure has been released. While either alternative requires finger pressure to operate against a spring, it is obvious that the spring'may be lighter where it is only required to return the clutch mechanism to normal position rather than move the platen itself.

Another important relationship in a machine of this kind is that all parts which are to be moved upon striking a key should begin their movement instantaneously upon initial movement of the key so that the machine will have the proper feel to the operator. Obviously, in 40 stenographic machines used for recording dictation, speeches, lectures, etc. where speed in recording is of the essence, it is almost essential that a relationship of this kind be established and maintained throughout the life of the machine. In the present invention, the proper feel to the machine is established by using with the type operating mechanism a clutch indicated generally at 24 which has the characteristic of instantaneously taking hold as soon as a key is struck and automatically adjusting itself to wear so that it is serviceable for substantially the life of the machine.

The clutch comprises a rotatable driver 25 which in the embodiment of the invention shown in the drawings consists of a collar rotatably mounted on a trunnion 23 of the platen. A dog 21 is pivoted'at 23 to the driver 25 in'a slot 23 which opens into the bearing surface 33 of the driver. The dog 21 has a block or law 3| comprising a planar shaft-engaging surface, and preferably, the shaft-engaging surface 3| is tangent to the shaft or tunnion 23 at a point which lies approximately 15 from the line between the cen-- ter of the shaft 26 and the center of the pivot 28. As the dog 21 is rocked on its pivot (see Fig. 4), the block 3| works in and out with respect to the shaft 23 to clutch and declutch the driver to and from the shaft.

The dog preferably is arched over the driver 25 so that the point of power application 32 is on the opposite side of the shaft from the pivot 23. In the form of the invention shown in Fig. 4, the face 3|. of the dog is constantly maintained in light contact with the shaft 23 by means of a small spring 33 which seats in a recess formed in the dog and engages the unslotted portion of the driver 25. Since the point 32 of power application is established, when all of the keys are at rest in their normal raised position, by the linkage which operates the clutch, and since the pivot 28 is capable of movement relative to the point 32, the spring 33 has the effect of rotating the driver 25 clockwise in Fig. 4 so that the surface 3| will always be in light contact with the shaft 25, and regardless of wear on the shaft 25 and the surface 3|, the spring 33 will accomplish this result. Therefore, when the point of power application 32 is moved upwardly by the clutch operating linkage, the point 34 of engagement between the shaft 23 and the surface 3| being already established, will cause the lifting of the dog 21 to instantaneously start rotation of the driver 25 and platen III in a counterclockwise direction.

When the point 32 of power application is moved down, by the release of the key, to the position shown in Fig. 4, the normal pressure exerted on the shaft. 28 by the block or law 3| is released except for the slight pressure exerted by the spring 33, and friction in the bearings of the platen in (small as it is), together with the inertia of the platen combine to prevent clockwise rotation of the platen while the clutch is returning to its normal position.

In Fig. 6, the clutch mechanism is inverted and gravity is relied upon to maintain a light pressure of the block 3| on the shaft 25 prior to operation of the clutch. In this embodiment of the invention, the clutch operating linkage must be such that a downward movement of the point 32 of power application is effected upon striking a key l2. The weight of the eccentric portion of the clutch mechanism will cause the driver 25 to rotate in a. clockwise direction (Fig. 6) until the block 3| is in light contact with the shaft 25, thereby maintaining at all times physical contact between the block and the shaft.

Although in both Fig. 4 and Fig. 6, the block 21 has been shown as a lever of the first class, it is obvious that levers of the second and third class may also be used, and preferably two of the points of'power application, fulcrumage, and resistance are located on opposite sides of the shaft.

In the embodiment of the invention shown in Figs. l-5 inclusive, the clutch 25 is actuated by linkage which includes a universal bar 35 always maintained in contact with the bottom edges of the key levers l3 by means of a toggle spring 35.

which extends between the frame II and upper toggle lever 31, the latter being connected at its upper end to a stud 33 extending laterally from the power end of the dog 21, and at its lower end to a second toggle lever 33 pivoted at 40 to the frame and having a link 4| which connects it to the universal bar lever 42 .whlch is adapted to rock on pivots and 44.

When a key 2 is struck, the universal bar 35 is moved downward a distance which is limited by the type bar i9 striking the platen and the resultant rocking of the universal bar lever 32 moves the floating pivot 45 of the toggle upward and to the right (Fig. 1) so that the point 32 of power application on the dog 21 is moved upwardly to rotate the platen Ill. The toggle connection is such that the platen completes its forward motion before the type'bar l3 strikes the platen.

Heretofore in machines of this character, the clutch mechanism has permitted considerable side play with the result that the platen would not begin its movement until after the keys had been moved downwardly a fraction of an inch, that distance being required to take up the side play. In the present invention, the dog 21 has an extended bearing surface in the slot 23 so that there is substantially no possibility of side play. Short travel of the platen which also results from side play or other lost motion in the clutch, or its associated linkage, is likewise avoided.

Another outstanding advantage of the arrangement disclosed and claimed herein is the fact that the clutch is substantially noiseless even after there has been considerable wear.

Since the clutch is self adjusting for wear, and there is substantially no possibility for lost motion or side play to occur, there is no place for noise to develop.

Experience has shown that dirt, rust, moisture and oil will not impair the operation of theclutch, and this is very important in reducing the amount of servicing that is necessary for the machine.

The invention may be variously embodied within the scope of the appended claims, and it will be understood that the invention may be used in other environment where a clutch of the characteristics described is desirable.

I claim:

1. A clutch comprising a rotatable drum, a collar mounted about said drum, said collar having a slot extending from the periphery of said collar into the center passageway occupied by said drum, a block or law pivoted in said slot and adapted to be swung upon its pivot into and out of engagement with said drum, an arm extending from said block out of said slot and parallel with the outer unslotted surface of said collar, and a spring operating between said arm and the unslotted portion of said collar to hold said block or jaw in clutching position, whereby the opening movement of said clutch is limited by the extended end of said arm in co-operation with the periphery of said collar.

2. A clutch comprising a rotatable drum, a collar mounted about said drum, said collar having a slot extending from the periphery of said collar into the center passageway occupied by said drum, a block or jaw pivoted in said slot and adapted to be swung upon its pivot so as to bring its gripping surface tangential with the periphery of said drum and into an engagement therewith, an arm extending from said block out of said slot and parallel with the outer unslotted surface of engagement with said drum, an arm extending from said block out of said slot and parallel with the outer unslotted surface of said collar, whereby the movement of said arm is limited between the clutching position of said block, on the one hand, and the co-action between the extended end of said arm and the unslotted periphery of said collar, on the other hand.

4. A clutch for actuating a rotatable shaft comprising a collar mounted about said shaft, said collar having a slot extending from the periphery of said collar into the center passageway occupied by said shaft, a block or jaw pivoted in said slot and adapted to be swung upon its pivot into and out of engagement with said shaft, anarm extending from said block out of said slot and arched about the outer unslotted surface of said collar, and a spring operating between said arm and the unslotted portion of said collar to hold the block or jaw in light physical contact with the shaft, whereby the opening movement of said clutch is limited by the extended end of said arm in cooperation with the periphery of said collar.

5. A clutch for actuating a rotatable shaft comprising a collar mounted about said shaft, said collar having a slot extending from the periphery of said collar into the center passageway occupied by said shaft, a block or jaw pivoted in said slot and adapted to be swung upon its pivot so as to bring its gripping surface tangential with the periphery of said shaft and into engagement therewith, an arm extending from said block out of said slot and arched about the outer unslotted surface of said collar, and a spring operating between said arm and the unslotted portion of said collar to hold said block or Jaw in light physical contact with the shaft whereby the opening movement of said clutch is limited by the extended end of said arm in cooperation with the periphery of said collar.

6. A clutch for actuating a rotatable shaft comprising a collar mounted about said shaft, said collar having a slot extending from the periphery of said collar into the center passageway occupied by said shaft, a block or jaw pivoted in said slot and adapted to be swung upon its pivot into and out of clutching engagement with said shaft, an arm extending from said block out of said slot and arched about the outer unslotted surface of said collar, whereby the movement of said arm is limited between the clutch position of said block on the one hand and the co-action between the extended end of said arm and the unslotted periphery of said arm on the other hand.

7. A clutch for use with a rotatable shaft, comprising a collar telescoped over the shaft, said collar having a slot extending from the periphery of the collar into the center passageway occupied by the shaft, a block or jaw pivoted in said slot and adapted to be swung upon its pivot to and from clutching engagement with the shaft, an arm extending from said block out of the slot and toward the side of the shaft opposite the pivot, and means for normally maintaining the block in physical contact with said shaft.

8. A clutch for use with a rotatable shaft, comprising a collar telescoped over the shaft, said collar having a slot extending from the periphery of the collar into the center passageway occupied by the shaft, a pin extending between, and supported by, the opposed walls of the slot, a block or jaw pivotally mounted within the slot on the pin, an arm extending from the block out of the slot and toward the side of the shaft opposite said pin, and adapted when moved in one direction to cause the block to have a clutching engagement with the shaft and to rotate it with the collar, and when moved in the otherdirection to cause the block to release the shaft and rotate the collar on the shaft.

ROBERT T. WRIGHT.

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