US1391922A - Driving and stopping mechanism - Google Patents

Description

L. E. TOPHAM.

DRIVING AND STOPPING MECHANISM.

APPLICATION FILED MAR. I4, I919.

1',391,922. Sept- 27,1921.

6 SHEETS-SHEET I.

. 4 I lmvemfjcr" L. E. TOPHAM. DRIVING AND STOPPING MECHANISM.

APPLICATION FILED MAR. 14, I919.

Patented Sept. 27, 1921.

6 SHEETS-SHEET 2.

1w Imver'JCcr"- MIST-3555 L. E. TOPH'AM.

DRIVING AND STOPPING MECHANISM.

APPLICATION FILED MAR-14,1919.

Patented Sept. 27-, 1921.

6 SHEETS-SHEET 3.

lmvervf czr" W L. E. TO'PHAM.

DRlVING AND STOPPING MECHANISM.

APPLICATION FILED MAR. 14, I919.

PatentedSept. 27,1921.

6 SHEETS-SHEET 4.

L. E. TOPHAM.

DRIVINGANDSTOPPING MECHANISM.

APPLICATIOH FILED MAR. 14, 1919- Patented Sept. 27,1921

"L. E. 'T0 PHAM. DRIVING AND STOPPING MECHANISM.

APPLICATION FILED MAR. 14, I919.-

1,3,91,9.22, PatentedSept; 27,1921.

6 SHEETS-SHEET e.

UNlTED STA'llES PATENT OFFICE.

LAURENCE E. TOPHAM, 0F SVIAM?SCOTT, EIASSAOH'USETTS, ASSIGNOR TO UNITED SHOE MACHINERY CORPORATION, OF PATERSON, NEWJERSEY, A CORPORATION OF NEW JERSEY.

DRIVING AND STOPPING- MECHANISM.

Specification of Letters Patent. Patented Sept. 2'7, 1921 Application filed, March 14, 1919. Serial No. 282,689.

ToaZZ whom it may concern:

Be it known that I, LAURENCE E. TOPHAM, a citizen of the United States, residing at Swampscott, in the county of Essex and State of Massachusetts, have invented certain new and useful Improvements in Driving and Stopping Mechanisms; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same. I

The present invention relates to driving and stopping mechanisms and more particularly to driving and stopping mechanisms for use in high speed machines which it is desirable to stop at a predetermined point in a cycle of operations.

Certain commercial driving and stopping mechanisms for such high speed machines are provided with high and low speed driving mechanisms, the machines being driven during the normal operations thereof by the high speed driving mechanism, and the low speed driving mechanism which is thrown in after the high speed driving mechanism is thrown out being designed to act first to reduce the speed of the machine and then to drive the machine at a low speedto stopping position.

One of the objects of the present invention is to provide a novel and improved driving and stopping mechanism of this type.

To this end a feature of the invention contemplates the provision of means whereby the resistance offered by the machine to being driven by the low speed driving mechanism is utilized to render devices active for stopping the machine. In the preferred embodiment of the invention such means comprises a driven member and a shiftable driving member that may constitute component parts of the low speed mechanism. These members are so constructed and arranged that when. the low speed mechanism has reduced the speed of the machine to its own speed, the driving member is shifted longitudinally which, through suitable mechanism, throws out the low speed mechanism. It is preferred to. employ positive stops for accomplishing the final stoppage of the machine when the low speed mechanism is thrown out, which steps may be controlled by said shiftable driving member, but if de sired the machine may be retarded and rangements' of parts hereinafter describedand claimed, the advantages of which will be obvious to those skilled in the art.

The several features of the invention will be readily understood from the following description and accompanying drawings in which:

Figure l is a view in side elevation of a machine provided with a driving and stopping mechanism embodying the present invention in its preferred form;

Fig. 2 is a plan view partly in section of a portion of the machine, illustrating the low speed driving mechanism, mechanism for shifting from the high to the low speed driving mechanism, and an additional braking mechanism; v

Fig. 3 is adetail sectional plan view of a portion of the locking pincarrier;

Fig. 4 is a rear elevation of the portion of the machine illustrated in Fig. 2;

Fig. 5 is a transverse sectional View of the head of the machine illustrating the portion thereof illustrated in Fig. 4 with a part of the additional braking mechanism removed;

Fig. 6 is a detail vertical sectional View of the locking pin carrier;

Fig. 7 is a vertical sectional view taken on a plane passing through the main shaft;

Fig.8 is a detail vertical sectional view of a portion of the low speed driving mechanism;

F 9 is a sectional view taken on the line 9 of Fig. 8; and

10 is a detail view in perspective of a member of the stopping devices.

Referring to Fig. l of the drawings, the machine is driven through a belt pulley 10 secured to the rear end of themain or cam shaft 12 and connected by a driving belt 1a with a pulley 16 mounted in the base of the machine. The pulley 16 is connected throughbeveled gears 18 with a sleeve 20 mounted on a driving shaft 22 and carrying one member 24 of the main driving clutch. The driving shaft carries the other member 26 of the clutch and also carries the driving pulley 28 through which motion is imparted to the shaft. The engagement of the members of the driving clutch is controlled through a treadle 30 connected with a clutch operating wedge 32. When the treadle is depressed the members of the driving clutch are forced into engagement and the machine is driven at a speed depending upon the pressure which the operator applies to the treadle. lVhen the treadle is released the clutch members are disengaged thus disconnecting the main shaft of the machine from the driving shaft. The upward movement of the treadle when it is released also throws into operation mechanism by which the main shaft is driven at a low speed and by which the shaft is stopped at a predetermined point in a cycle of operations as will be hereinafter described.

The low speed driving mechanism comprises a forwardly driven friction clutch consisting of clutch members 3 and 36 (Fig. '7.) The clutch member 34 is formed on a spiral. gear or worm wheel 38 which is loosely mounted on the main shaft and is driven during the operation of the machine by a spiral gear or worm 10 (Figs 5 and 8) secured to a shaft Q2. The shaft 42 is continuously driven from the driving pulley 28 (Fig. 1) through a belt 44 passing over a pulley formed on the hub of the pulley 28 and over a pulley 46 secured to the shaft 42. The other member 36 of the clutch is formed on a flange projecting from a sleeve &8 which is loosely mounted on the main shaft 12. The sleeve is free to slide longitudinally on the shaft but is connected to rotate with the shaft by means of a block 50 secured to the pulley l0 and arranged between lugs 52 projecting radially from the sleeve 48. The sleeve is held normally in position with the Clllti'll members out of engagement by a spring 54 arranged in a recess in the block 50 and interposed between the bottom of the recess a the head of a bolt which carries a plate 56 engaging the lugs 52. The normal position of the clutch sleeve is determined by an adjustable stop-screw 60. When the clutch members 3st and 36 are engaged they act as a friction brake to absorb the energy due to the momentum of the main shaft until the shaft is rotating at the same speed as the clutch member 34 after which the main shaft is driven forward at a predetermined low speed by the clutch until the clutch is disengaged and the shaft is brought to rest at predetermined point in a cycle of operations of the machine by the action of the stopping devices hereinafter described.

The low speed clutch is thrown into operation a predetermined time in the cycle of operations of the machine and to this end mechanism is provided comprising a timing cam that consists of a cam groove 62 (Fig. 2) formed on the sleeve 48 and engaged by a roll on one end of a bell crank lever 64. p The other end of the bell crank lever is provided with a recess 66 adapted to receive a locking pin 68 (Figs. 4 and 5) which is normally held out of engagement with the lever so that during the normal running of the machine the lever is oscillated idly by the cam. When the treadle is released to throw out the high speed mechanism and stop the machine, the locking pin 68 is forced upwardly against the underside of the bell crank lever and when the recess in the lever registers with the pin. the pin snaps into the recess. The cam 62 is so timed that the recess in the end of the bell crank lever is brought into position to register with the locking pin at a definite point in the rotation of the main shaft. When the locking pin is engaged with the bell crank lever, the lever is held from movement about its pivot, whereupon the cam 62 and the roll carried by the lever coiiperate to shift the clutch sleeve 48 to bring the members of the low speed clutch into engagement. The locking pin is mounted on the end of a sliding carrier 70 which is held in normal position by a spring 7 2. The spring surrounds a bolt 74 extending from the rear end of the carrier, and is interposed between a shoulder on the carrier and the inner end of an adjustable screw threaded sleeve 7 6. The bolt 74L carri-es a nut 78 which engages the other end of the sleeve and holds the spring under compression. By adjusting the nut the com pression of the spring may be varied and by adjusting the sleeve 7 6 the slide may be adjusted to bring the locking pin into proper register with the recess in the end of the bell crank lever 64. The locking pin is forced in a direction to engage with the bell crank lever by a spring 80.

In order that the mechanism for throwing the slow speed clutch into operation may be under the control of the operator the locking pin is held down out of engagement with the bell crank lever so long as the treadle 30 is depressed and the main driving clutch is actuated to drive the machine. The mechanism for thus controlling the engagement of the locking pin with the recess 66 in the arm of the bell crank lever comprises a link 8-1 (Fig. 5) pivotally connected with a block secured to the lower end of the locking pin and connecting said pin with the arm 86 of a three-arm lever 87 secured to a rock shaft 88. This lever is provided with a second arm 90, on the end of which is mounted a roll 92. The locking pin is held down out of engagement with the recess 66 in the arm of the bell crank lever while the treadle is depressed and the main driving clutch in the base of the machine is engaged, by the engagement with the roll 92 of a cam face 94 formed upon the outer end of an arm 96 that ispiv'oted upon a stud 98 and connected with the forward end of the treadle by means of a rod 100. The cam face 94 is formed substantially concentric with the path of movement of the outer end of the arm 96 so that the movements of the treadle in producing variations in the speed of the machine will not effectthe position of the locking pin. When the treadle is released and rises, the arm 96 is swung upwardly to disengage the outer end thereof from the roll 92 and the locking pin is then forced upwardlyby the spring 80 into engagement with the under side of the bell crank lever and when the recess 66 registers with the head of the pin, the pin snaps into the recess. When the treadle is depressed to I start the machine, the outer end of the arm upon an axis substantially parallelwith the 96 engages the roll 92 and thereby swings the three-arm lever to disengage the lockin pin from the recess in the arm of the bel crank lever. The parts are constructed and arranged so that the locking pin is disengaged from the recess 66 before the main driving clutch is engaged and the continued downward movement of the treadle to engage the main driving clutch brings the cam face at the outer end of the arm 96 into engagement with the roll 92.

For finally arresting'the movement of the main shaft when the low speed driving mechanism is thrown out of operation, as hereinafter described, a cam 104 (Fig. 5) is carried by the main shaft and is provided with a projecting stop-lug 106 adapted to engage a stop shoulder 108 formed on a lever 110 to stop the shaft in a predetermined angular position. upon a rocking sleeve 112 that is mounted on a stud 114 arranged substantially parallel with the main shaft 12 of the machine so that the lever 110 is arranged to swing axis of said shaft. The cam 104, when the lever 110 is moved into the path thereof, is.

arranged to swing said lever and the sleeve 112 on which it is carried to the right (Fig. 5) about the stud 114. The lever 110 is actuated by the cam 104 as the shaft is executing its final forward movementjust before it isbrought to rest. To enable the lever 110 to be moved into and out of the path of the cam, said lever is pivotally con-1 nected with the sleeve 112 by pivot pins 116 secured in arms on the lever and ar ranged at right angles-to the axis of the sleeve, the inner ends of which engage in sockets in the sleeve 112. The lever 110 is provided with a laterally extending arm 118 (Fig. 4) the endof which projects forwardly at an angle to the main portion thereof across the end of the stud 1'14 and carries an abutment screw 120 arranged substantially in line with the axis of the stud.

The lever 110 is mounted A coiled spring 119 is connected to the arm 118 and acts to swing the lever 110 into the path of the cam 104. The lever 110 is maintained out of the path of the cam 104 when the treadle is depressed by the engagement of an arm 122 of the three-arm lever 67 with the end of the screw 120. When the treadle is depressed, the three-arm lever'87 is actuated by the engagement of the arm 96 with the roll 92 to lift the arm 122 and thereby swing the lever 110 about the pivot pins 116 so as to place the shoulder 108 on the lever 110 at one side of the path of the cam 104 and the lever 110 is held-in this positionwhile the roll 92 is engaged with the cam face on the outer end of the arm 96.

In certain driving and stopping mechanlsms heretofore proposed employing a low speed driving mechanism similar to the one illustrated in the drawings, the low speed driving mechanism is maintained in operation only for a predetermined number of degrees of rotation of the main shaft, where upon a timing cam corresponding to the cam 62, acts to throw out the low speed driving mechanism and positive stops are brought into engagement tostop the ma- I chine even through the speed thereof has not been reduced sufficiently to allow tive stops to act without danger of injuring the parts of the machine by undue shock or jar. Accordingly, in the illustrated embodiment of the invention the timing cam 62 is not permitted to throw out the low speed mechanism and also the lever 110 is held out of the path of the stop cam 104, until such time as the speed of the main shaft has been reduced tothat of the low speed mechanism. When the speed of the main shaft, however, has been thus reduced, means are rendered active which positively hold the bell crank lever from movement by the low' part 123 of the timing cam so that when this part of the cam engages the cam roll these parts cooperate to throw out the low speed mecha nism. This means also permits the lever 110 to be swung into the path of the stop cam 104.

Such reduction in the speed of the machine before finally stopping at a predetermined point may, in some cases, require that the low speed driving mechanism act for more than one rotation of the main shaft, but, in any case, the desired stoppage of the machine will occur in the shortest time, after the treadle is released, that is possible without danger of injuring the parts of the machine by undue shock or jar.

As the release of the treadle renders the timing cam 62 active by the locking engagement of the locking pin 68 with the recess in the end of the bell crank lever 64, the carrier 70 will be forced forwardly a certain amount against the action of its spring 72 the posi- Q by the engagement of the cam roll on the bell crank lever with the high part of the timing cam. This movement of the carrier is such as to bring avertical slot 126 in the carrier into registry with a latch pin 128 connected with the upper end of the lever 110. In order that the position of the latch pin may be adjusted so that the slot 126 may register therewith at the limit of the forward movement of the carrier, the pin extends through and is guided by a cylindrical aperture in an eccentric bushing 180 adjustably secured in a clamp in the form of a split collar 182 formed on a bracket 134 which is secured by screws 136 to the frame of the machine. The collar firmly grips the bushing by means of a bolt 138, which bolt may be loosened to allow for the desired adjustment of the latch pin by turning the eccentric bushing 180, the bushing being provided with a knurled flange 140 for this purpose. To provide for such adjustment of the latch pin and also to allow for movement of the lever 110 in a plane transverse to the main shaft 12 by the action of the cam 104, the pin is connected to the upper end of the lever 110 by means of a link 142 having universal ball and socket joints at its ends. 7 The latch pin 128 is maintained out of engagement with the slot 126 during the speed reducing action of the low speed mechanism by the lever 110 and in turn this lever is maintained out of the path of the cam 104 by the arm 122 of the three-arm lever 87. To this end, the rock shaft 88 to which said three-arm lever is secured, carries a downwardly extending arm 146 (Figs. 4 and 5),

which arm is provided with gear teeth which mesh with teeth on the end of an arm 148 secured to one end of a rock shaft 150. On the other end of said rock shaft is secured an arm 152 which is provided with gear teeth that mesh with rack teeth formed .on a sleeve or bushing 154 (Figs. 8 and 9) in which is journaled the shaft 42 that carries the worm or driving spiral gear 40 of the low speed driving mechanism. The bushing 154 is interposed between the worm 40 and the pulley 46 secured to the shaft 42. The bushing is mounted for longitudinal movement in a bearing 156 on the frame of the machine. Such longitudinal movement of the bushing is limited in one direction by the engagement of the worm 40 with one end of the bearing and in the opposite direction by the engagement of the pulley 46 with the other end of the bearing.

During the speed reducing action of the low speed driving mechanism, the member of the low speed clutch which is carried by the main shaft 18 will tend to drive the clutch member carried by the worm wheel 38 at a greater speed than the worm 40 drives said worm wheel, so that the teeth of the worm wheel .will act to shift the worm 40 and the bushing 154 to the right, viewing Fig. 8, to the position indicated by dotted lines, in this figure. Such positioning of the worm and bushing will, through the mechanism connecting these parts with the arm 122 of the three-arm lever 87, maintain said arm in a sufiiciently elevated position to hold the stop lever 110 out of the path of the stop cam 104 and the latch pin 128 out of engagement with the slot 126. When, however, the speed of the machine has been reduced to the speedof the low speed driving mechanismso that such mechanism acts to drive the machine, the resistance offered by the machine to being driven by the worm 40 will at once shift the worm and bushing to the position of these parts indicated in Fig. 5 and in full lines in Fig. 8. This movement of the worm and bushing will, through the connecting mechanism, depress the arm 122 (Fig. 5) sufficiently to allow the stop lever 110 to be carried by its spring into the path of the stop cam 104 as soon as the slot 128 in the locking pin carrier registers with the latch pin 126 which occurs when the high part of the timing cam 62 engages the cam roll. The engagement of the latch pin 68 with the slot in the locking pin carrier 70 results in the latch pin coperating with the forward end of the slot to positively limit the rearward movement of the carrier, so that when the lower part of the cam approaches the cam roll on the bell crank lever 64, the lever is held from movement which causes the cam roll to coiiperate with the cam to disengage the members of the low speed clutch. At this time, the lug 106 on the stop cam 104 engages the stop shoulder 108 on the lever 110 which finally arrests the rotation ,of the main shaft in a predetermined angular position. a v In order to permit said movements of the three-armlever after the treadle is released without disturbing the position of the looking pin 68, a certain amount of lost motion is provided between the lever and the link 84 which connects the lever and locking pin, the link being furnished with a slot 157 for this purpose. J An additional braking mechanism is illustrated in the drawings which is rendered active shortly before the stop lug on the cam 104 engages the shoulder on the lever 110. This braking mechanism assists in slowing down the machine to stopping position and also serves to maintain the parts of the machine in position while the machine is at rest. This braking mechanism is shown best in Figs. 2, 4 and 5, and comprises an arm 160 (Fig. 5) secured to the rocking sleeve 112, which arm is connected to abrake shoe 162 for engagement with a side of the pulley 10 on the main shaft of the machine, such that when the stoplever 110 is swung outwardly by the rise 164 on the cam 104, the arm 160 is carried therewith which, through the connecting mechanism, actuates the brake shoe 162. This connecting mechanism comprises a link which consists the upper end of the arm 160 with the upper end of a lever 166 (Fig. 4) that is pivoted on a stud 168, and the lower end of said lever is provided with a screw 170. The projecting end of said screw engages the end of an arm 172 of a bell crank lever 174, the other arm of which carries the brake shoe 162, so that when the arm 160 is swung outwardly this bell crank lever is actuated to carry the brake shoe into operative engagement with the pulley 10 against the action of a coiled spring 176 that is connected at one end to the bell crank lever and at its other end to the frame of the machine. When the braking mechanism is thus set, the parts thereof are held in position and the stop shoulder on the lever 110 is prevented from dropping into a clearance recess 17 8 in the cam 104, by a latch pin 180, which engages a projecting pin 182 at the upper end of the lever 166. The latch pin 180 is secured to the upper end of an arm 184 that is formed on one end of a rock shaft 186, having its axis arranged in a plane transverse to the axis of the lever 166. An arm 188 is secured to the other end of said rock shaft and its free end engages a stop lug formed on the laterally extending arm of the stop lever 110. When the lever 110 is moved into the path of its cam, the laterally extending arm is swung downwardly which permits the arm 188 to swing downwardly by gravity so that when the pin 182 on the lever 166 passes the end of the latch pin 184, the latter snaps into position.

When the lever 110 is swung out of engagement with the stop cam 104, by depressing the treadle, the laterally extending arm of said lever acts through the arm 188 to retract the latch pin 184, thereby allowing the spring 17 6 to bring the members of the braking mechanism to their normal inoperative position.

While it is preferred to employ the specific construction and arrangement of parts shown and described, it will be understood that this construction and arrangement is not essential except so far as specified in the claims and may be changed or modified without departing from the broader fea tures of the invention.

The nature and scope of the invention having been indicated, and a mechanism embodying the several features of the invention in their preferred form having been specifically described, what is claimed is 1. A driving and stopping mechanism having, in combination, a shaft, a high speed driving mechanism therefor, a low speed driving mechanism therefor, means for shifting from the high to the low speed mechanism, said low speed mechanism constructed to act first to reduce the speed of the shaft and then to drive the shaft at a low speed, stopping devices for the shaft, and means whereby the resistance offered by the shaft to the actuation thereof by the lOW speed mechanism is utilized to render the stopping devices active.

2. A driving and stopping mechanism having, in combination, a driven member, a variable speed driving mechanism therefor, a constant speed driving mechanism therefor, means for shifting from the variable to the constant speed mechanism, said constant speed mechanism constructed to act first to change the speed of the driven member to its speed and then to drive the driven memher at a constant speed, stopping devices for the driven member, and means whereby the resistance offered by the driven member to the operation of the constant speed mechanism is utilized to render the stopping devices actives Q 3. A driving and stopping mechanism having, in combination, a shaft, ahigh speed driving mechanism therefor, a'low speed driving mechanism. therefor, means for shifting from the high to the lowspeed mechanism, said low speed mechanism constructed to act first to reduce the speed of the shaft and then to drive the shaft at a low speed, stopping devices for the shaft, and means whereby the resistance offered by the shaft. upon being driven at said low speed, is utilized to render the stopping devices active.

4. A driving and stopping mechanism having, in combination, a driven member, a high speed-driving mechanism therefor, a low speed driving mechanism therefor, means for shifting from the high to the low speed mechanism, stopping devices for the driven member, and means whereby the resistance offered by the driven member to the driving action of the low speed mechanism is utilized to render the stopping devices active.

'5. A driving and stopping mechanism having, in combination, a shaft, a high speed driving mechanism therefor, a low speed driving member constructed to act first to reduce the speed of the shaft and then to drive the shaft at a low speed, means for actuating the low speed driving member, means for shifting from the high speed mechanism to the low speed member, stopping devices for the shaft. and means where by the driving action of the shaft during said speed reducing action of the low speed member is utilized to maintain the stopping devices inactive and the resistance offered by the shaft during said driving action of the low speed member is utilized to render the stopping devices active. v r

6. A driving and stopping mechanism having, in combination, a shaft, a high speed driving mechanism therefor, a low speed driving member constructed to act first to reduce the speed of the shaft and then to drive the shaft at a low speed, means for actuating the low speed driving member, means for shifting from the high speed mechanism to the low speed driving member, stopping devices for the shaft, means for maintaining the stopping devices inac tive during said speed reducing action of the low speed member, and means whereby the resistance offered by the shaft during said driving action of the low speed member is utilized to render the stopping devices active.

7 A driving and stopping mechanism having, in combination, a shaft, a high speed driving mechanism therefor, a low speed driving mechanism constructed to act first to reduce the speed of the shaft and then to drive the shaft at a low speed, means for shifting from the high to the low speed driving mechanism, said low speed driving mechanism comprising a pair of spiral gears one of which is adapted to be moved 1ongitudinally in one direction by the combined action of the teeth of the spiral gears when the low speed mechanism acts to drive the shaft at a low speed, and means rendered active by said longitudinal movement of one of the spiral gears for stopping the shaft.

8. A driving and stopping mechanism having, in combination, a shaft, a high speed driving mechanism therefor, a clutch member carried by the shaft, a cooperating clutch member loose on the shaft, mechanism for driving the latter clutch member at a low speed, means for disconnecting the high speed mechanism and connecting the clutch members whereby the clutch member loose on the shaft acts to reduce the speed of the other clutch member and then to drive it in unison therewith, stopping devices for the shaft, means actuated by the clutch member carried by the shaft for maintaining the stopping devices inactive during the speed reducing action of the other clutch member, and for rendering the stopping devices active when the clutch members are driven in unison.

9. A driving and stopping mechanism having, in combination, a shaft, a high speed driving mechanism therefor, a clutch member carried by the shaft, a cooperating clutch member loose on the shaft, mechanism for driving the latter clutch member at a low speed, means for disconnecting the high speed mechanism and connecting the clutch members whereby the clutch member loose on the shaft acts to reduce the speed of the other clutch member and then to drive it in unison therewith, stopping devices for the shaft, means for maintaining the stopping devices inactive during the speed reducing action of the clutch members, and means whereby the resistance offered by the clutch member carried by the shaft during the driving action of the other clutch member is utilized to render the stopping devices active.

10. A driving and stopping mechanism having, in combination, a shaft, a high speed driving mechanism therefor, a low speed driving mechanism constructed to act first to reduce the speed of the shaft and then to drive the shaft at a low speed, means for shifting from the high to the low speed mechanism, said low speed mechanism comprising a drivin member and a driven mem ber constructed to cooperate to shift one of said members to one position during the speed reducing action of the low speed mechanism and, to shift the latter member to another position during said driving action of the low speed mechanism, and means controlled by said shifting movements of one of said membersfor stopping the shaft.

11. A driving and stopping mechanism having, in combination, a shaft, a high speed driving mechanism therefor, a speed reducing mechanism for the shaft, means for disconnecting the high speed mechanism and for rendering'the speed reducing mechanism active, stopping devices for the shaft, and means whereby the resistance offered by the shaft to the speed reducing mechanism after the speed of the shaft has been reduced to a predetermined point is utilized to render the stopping devices active.

12. A driving and stopping mechanism having, in combination, a shaft, a high speed driving mechanism therefor, a speed reducing mechanism for the shaft, means for shifting from the high speed mechanism to the speed reducing mechanism, said speed reducing mechanism comprising a pair of spiral gears one of which is adapted to be moved longitudinally in one direction by the combined action of their teeth when the speed of the shaft has been reduced to a predetermined point, and means rendered active by said movable spiral gear during the longitudinal movement thereof for ship ping the shaft.

13. A driving and stopping mechanism having, in combination, a shaft, a high speed driving mechanism therfor, a low speed driving mechanism therefor, means for shifting from the high to the low speed mechanism, said low speed mechanism constructed to act first to reduce the speed of the shaft and then to drive the shaft at a low speed, stopping devices for the shaft, and means actuated by movement of a member of the low speed mechanism for rendering the stopping devices active, such movement of said member being dependent upon the establishment of effective driving connection between the shaft and the low speed mechanism.

14. A. driving and stopping mechanism having, in combination, a driven member, a 5 high Speed driving mechanism therefor, a

low speed driving mechanism therefor constructed to act first to reduce the speed of the driven member and then to drive the driven member at a low speed, and means for shifting from the high to the low speed mechanisms and for utilizing the resistance offered by the driven member to the actuw tion thereof by the low speed mechanism to disconnect the low speed mechanism and the driven member. I

LAURENCE E. TOPHAM.

Images