US2402450A - Tracer controlled feed mechanism for machine tools - Google Patents

Description

June 18, 1946.

vC. K. SALlSBURY TRACER GONTEOLLED FEED MECHANISM MACHINE TOOLS Filed Apri1 1, 1943 15 Sheets-Sheet l June 18, 1946. c. K. sALlsBURY 2,402,450

TRACER CONTROLLED FEED MECHANISM FOR MACHINE TOOLS Filed April 1, 194s 15 snags-sheet s June 1s, 1946.

c. K. sALlsBURY 2,402,450

TRACER CONTROLLED FEED MECHANISM FOR MACHINE TOOLS Filed April i', 1945 15 sheetssheet 4 `lime 18, 1946. Q K SALISBURY 2,402,450

TRACER CONTROLLED FEED MECHANISM FOR MACHINE TOOLS Filed April l, 1943 15 Sheets-Sheet 5 Wvg/WMD June 18, 1946. c. K. sALlsBURY TRACER GONTROLLED FEED MECHANISM FOR MACHINE TOOLS Filed April 1, 1945 15 sheets-sheet e June 18,:1946. Q K sALlSBURY 2,402,450

TRACER GONTROLLED FEED MECHANISM FOR MACHINE TOOLS 15 Sheets-Sheet '7 Filed April l, 1945 M kfw June 18, 1946. c. K. SALISBURY l 2,402,450

TRACER CONTROLLED FEED MECHANISM FOR MACHINE TOOLS Fi'led April l, 1945 l5 Sheets-Sheet 8 //1/ V51/7W ZM @www June 18, 1946. c, K. sALlsBURY 2,402,450

TRACER CONTROLLED FEED MECHANISM FOR MACHINE TOOLS Filed April 1, 1945 l5 Sheets-Sheet 9 WVM/7l?? ZM @fw June 18, 1946. c. K. sALlsBURY 2,402,450

TRACER CONTROLLED FEED MECHANISM FOR MACHINE TOOLS Filed 1p1-i1 1, 194:5 15 sheets-sheet 1o June 18, 1946. c. K. SALISBURY 2,402,450

TRACER' CONTROLLED FEED MECHANISM FOR MACHINE TOOLS Filed April l, 1945 -15 Sheets-Sheet ll 26o #of .V61 O I o June 18, 1946. Q K SAUSBURY l 2,402,450

TRACER CONTROLLED FEED MECHANISM FOR MACHINE TOOLS Filed April l, 1945 15 Sheets-Sheet 12 June18,1946. 3, K, SAUSBURY L 2,402,450

TRACER CONTROLLED FEED MECHANISM FQR MACHINE TOOLS Filed April 1, 1943 15 Sheets-Sheet 15 .lune 18, 1946. c. K. sALlsBURY 2,402,450

TRACER CONTROLLED FEED MECHANISM FOR MACHINE TOOLS Filed Apri1 1, 1945 15 Sheng-sheet 14 June 18, 1946. c. K. sALIsBURY TRACER CONTROLLED FEED MECHANISM FOR MACHINE TOOLS Filed April l, 1945 l5 Sheets-Sheet l5 4-39 Fig 55 WVM/75A? @Mew mm? Patented .Func 18,A 1946 @FFME TRACER CONTROLLED FEED MECHANISM FOR MACHINE TOOLS Charles K. Salisbury, Waterloo, Iowa l Application April 1, 1943. Serial No.481,486

' (ci. sz--m 26 Claims. l

My invention relates to tracer controlledieed mechanism for machine tools.

The objects of my invention are; to provide a tracer controlled machine tool adaptedto automatically finish work by a series of graduated cutting operations taken in one direction, to pro-l vide such mechanism with high speed return of the tool to the starting point, to provide suitable forms for the cutting tool, pattern, and tracer point to accurately machine the work when cut in one direction, to provide means to vary the cutting depth in successive automatically controlled cutting operations, to provide means to reverse the direction of feed of electrically controlled mechanism by superimposed mechanical control without change in the electrical control circuits', to provide a direct acting cutting pressure control mechanism for reciprocating mechanism that is variable as to the pressure developcd in opposite feed directions, to provide a cutting pressure control of that nature that becomes operable at a predetermined cutting pressure, to provide a two-way roller clutch in which the rollers are held in pressed contact with the active surface of the driven clutch member to reduce wear and to aid the return of the rollers to their inoperative position upon disengagement.

to provide a swinging and telescoping drive shaft `contour of the pattern, to provide a pattern that is readily formed from micrometer or comparator measurements, and correctly set through tracer co-operation, to eliminate tool chatter in tracer controlled cutting mechanism by balanced cutting pressure, to provide a tool setting indicator' to co-operate with-the pattern and'tracer for rapid adjustment of the tool, to provide a tracer having overlapping ieed controls that is adjustable as to the tracer movement required between in-feed and out-iced contact positions, to provide increased tool cutting speed during the iinishing operation, to provide a tracer controlled roller clutch in which the driven member is provided with .inclined driving surface, to'provide a tracer bar so mounted as to yield to undue pressure and to simultaneously disconnect from control, to provide a two-way roller clutch using variable leverage to change the feeding rate, to provide abutment stops co-operating with cutting pressure control mechanism to limit the movements of the slides, to provide an electrical feed stop comprising means to interrupt one of the cycle out of control, to provide an electrically controlled lock for the power feed in one direction when a slide has reached a predetermined limit, to provide a yielding contact plate moving with the tracer to Contact the pattern electrically to actuate reversing mechanism, to provide a mechanical reversing mechanism actuated by movement of a slide, and to provide means to stop the action of electrically controlled mechanism by superimposing mechanical control without -change in the electric control circuits.

With the above and other objects in view, my invention consists of the mechanism herein described and shown in the drawings, in which:

Figure 1 is a plan view of a machine tool controlled by the mechanism herein described.

Figure 2 is an end view of the mechanism shown in Figure 1 with the tail stock support removed.

Figure 3 is a plan view of one unit of the reciprocating power clutch mechanism in its foundation case, with the case cover removed. It shows parts common to both control units with the eX- ception of those parts used only with the carriage control unit which have the reference letter a in addition to the reference numeral.l

Figure 4 is a sectional view of the roller clutch and its mechanical control mechanism assembled on its shaft and taken on line 4 1! of Figure 3. It shows parts common to both units with the exception of those parts which carry the reference letter a used only with the carriage control unit. Figure 5 is a sectional view of the variable leverage control, taken on line 5--5 of Figure 3.

Figure 6 is a sectional View of the cutting pressure control, taken on line 6 6 of Figure 3.

Figure 9 is a cross sectional view of the clutch and its mechanical controls, taken on line 9--9 of Figure 3.

Figure 10 is a side view of the clutch roller cage and its associated control mechanism, in partial controlling electric circuits, while that circuit is with the rollers deflected by thel cage to the driving position.

Figure 13 is a side view of the hook-up mechanism, sectioned on line i3|3 of Figure 3.

Figure 14 is a plan view of the hook-up mechanism sectioned on line ll-il of Figure 13.

Figure 15 is a side sectional view of one of the control coils with its armature and associated parts, taken on line i5-I5 of Figure 3'.

Figure16 is a side sectional view of the cross slide actuating telescoping power shaft taken through its complete length, sectioned on line iii-I6 of Figure 17.

Figure 17 is a rear view of the upper end of the mechanism shown in Figure 16.

Figure 18 is a bottom view of the mechanism shown in Figure 17, sectioned on line i8-I8 of Figure 17.

Figure 19 is an adaptation of the upper end of the telescoping power shaft shown in Figures 16, 17, and 18, where a reducing gear is incorporated in the drive to operate the lead screw, and is sectioned on line I9-I9 of Figure 2.

Figure 20 is a sectional view of a simplified rotation operated feed stop, sectioned on line 20-20 of Figure 21.

Figure 21 is an end view of the mechanis shown in Figure 20, taken from the contact end.

Figure 22 is a cross sectional view of the mechanism shown in Figures 20 and 21, sectioned on line 22--22 of Figure 20.

Figure 23 is the top view of a templet formed for cutting in one direction, and also showing the tool setting plate carried thereby.

Figure 24 is the top view of the tool setting indicator in its relation to the tool setting plate shown in Figure 23.

Figure 25 is an end view of the mechanism shown in Figure 23.

Figure 26 is an end view of the tool setting indicator in its relation to the mechanism shown in Figure 25, with the indicator bar foldedto the inoperative position as shown by dash and dot lines.

Figure 27 is a sideview of the indicator base in position taken when folded, and with indicator bar withdrawn.

Figure 28 is the plan view ofthe tracer and its cutting adjustment control, with the tracer cover removed.

Figure 29 is a cross sectional view of the mechanism shown in Figure 28, taken on line 29-29 of Figure 28.

Figure 30 is an end view of the tracer and a portion of the feed control for the tracer.

Figure 31 is a plan view of the tracer contact lever.

Figure 32 is a cross section of the contact springs taken on line 32-732 of Figure 28 to show relation of the parts.

Figure 33 is a cross section of the contact springs, taken on line 33-33 of Figure 28, showing the insulated overlapping feed control plate of one set. v

Figure 34 is a side view of the safety tracer bar in the position taken when deflected by undue pressure.

Figure 35 is a slightly enlarged side view of the pattern contacting electrical control for power reverse. l

Figure 36 is a plan view of the mechanism shown in Figure 35, showing action when contacting the pattern and when following a shoulder on the pattern.

Figure 37 is a side view of the tracer feed control mechanism and reversing control, with parts in position for cutting operation.

Figure 38 is a cross sectional view ofthe mechanism' shown in Figure 37, taken on line II- of Figure 28.

Figure 39 is a view of the tracer depth control mechanism and support, taken `on line 39-38 oi' Figure 1.

Figure 40 shows the escapement plate and the escapement detent removed from the mechanism to show relative position during the cutting movement.

Figure 41 is the rear end view of the electrically controlled locking and reversing mechanism. showing position of the parts during the return movement.

Figure 42 is a sectional view of the mechanism shown in Figure 41, taken on line 42-42 of that figure.

Figure 43 shows the circuit control plate removed from the mechanism to show rotated position relative to the bearing cap and the contact arm during the return movement.

Figure, 44 is plan view of the hydraulic control of the variable leverage speed control mechanism.

Figure 45 is a sectional view of the mechanism shown in Figure 44, taken on line 45-45 of Figure 44. All parts are common to both control units with the exception of those parts which carry the reference letter a which are used only with the carriage control unit. It shows a partial section through the foundation case and the base support t0 show relative mounting.

Figure 46 is a sectional view of the outlet control valve of the hydraulic mechanism, taken on line 46--46 of Figure 44.

Figure 47 is a plan view of the cutting speed control switch and also the feed stop switch.

Figure 48 is a sectional view of the mechanism shown in Figure 47, taken on line 48--48 of that figure.

Figure 49 is a side view of the manual resetting device for tracer cutting depth and stop switch mechanism.

Figure 50 is a cross sectional view, taken on line 50-50 of Figure 49.

Figure 51 shows balanced cutting pressure operation of the cutting tool.

Figure 52 is a diagram of the electric connections.

Figure 53 is a diagrammatic showing of cutting operations.

Figure 54 is a modified mechanical reversing control.

Figure 55 is a side view of the modification shown in Figure 54.

Figure 56 is a top view of the trip mechanism of the reverse mechanism shown in Figures 54 and 55.

Figure 57 is a modified depth control plate.

It will be noted that to show a completeoperable mechanism, a lathe has been chosen for illustration. It is understood that any mechanism controlled by a pattern is included.

A lathe having a bed 62, Figures l and 2, has a work spindle 63 adapted to rotate a workpiece 64 (Figure 1).

A carriage 65 slides on the bed and carries a cross slide 66 which is provided with a compound rest 61 on which a cutting tool 68 is supported to operate on the work. Two two-piece brackets, 169 and 10, are rigidly Xed to the rear of the lathe bed. These carry a pattern supporting base rail 1I provided with a vertical wall 13, and secured to the brackets in planes parallel with the turning axis of the lathe.

A pattern composed of a formed control portion i4 and a base portion 324 (Figure ,1) rigidly secured thereto, is fixed to the base rail by screws 16.

The carriage is moved in either direction by a lead screw 'il' (Figures 1, 2, and 19) while the cross slide is moved by a cross feed screw 18 (Figures 1, 16, 17, and .18).

The lead screw and the cross feed screw are operated by independent individual roller clutcx units that are identical .in construction and in operation in al1 parts used in control of the cutting feeds. However, the lead screw operating unit has additional parts that operate only during the return movement of the carriage. These additional parts control the speed of'carriage return and reversef and lock the lead screw. Those parts common to the operationof both units carry the same reference numbers in both units', but those parts added or changed to operate only with the lead screw, carry the reference letter a also. This also applies to the special parts of the swinging drive shaft.

The rear end of the cross feed screw 18 extends through a bushing 8|, Figure 16, which is in a plate 82 secured to the rear of the carriage by bolts 83, Figure 16.

A miter gear 8| (Figures 16 and 18) on the screw 18, is driven by a key B5 (Figure 16) to rotate with the screw and is locked thereto by a sleeve 8-6 and a nut 8Ton the screw.

A gear housing 80, Figures 2, 16, and 17, is supported on the sleeve and is free to swing thereon.

The housing carries a miter gear 90 which meshes with the gear 84 and is secured to the Y upper end of a drive shaft 9| by a key 02 (Figure 16). This shaft is free to turn in a bearing 93 secured to the gear housing by bolts 94.

extending through a bearing sleeve |05 secured by bolts |01 to a gear housing |08.

The housing is free to swing on a sleeve |00' secured by a nut ||0 to the end of a roller clutch shaft ISI which has a miter gear H2 secured thereto by a key iid for clutch drive.

The clutch unit operating the cross slide is housed in a foundation case |30, Figures 1 and 2, while that operating the lead screw is housed in |3011, Figures l. 2, and 3, which differs from |30 because of a clearance |8|a in the cover |32a.

It is desirable that a reduction gear be used in the drive of the lead screw. The reducing gear ||'|a Fig. 19 is keyed at ||6a to the end of the lead screw and meshes with a pinion lia made integral with a miter gear Nga. A bearing sleeve |20@ extends through the bore of ||8a and ||9a, and they are free to turn on a stud |2|a fixed in a plate i22a secured to thef bed of the lathe by bolts |2311.

A gear housing |2||a freely swings on the stud and is retained by a nut |25a and a lock nut |26a.

The remaining parts of the shaft are identical with those of the shaft used in cross slide operation.

It `is not possible to provide speed change directly in the drive shaft gear, where used in driving the cross slide, as the movement of the carriage would result in a change in the setting of the tool and tracer. However, the gear reduc.

non may be at the lower end of the drive and be.

integral with the operating unit, for either drive (not shown). The foundation cases |80 and |30a are preferably secured to the floor foundation, independent of the lathe. by means of bolting lugs |33, Figures l, 2, and 3. as this permits of ready installation and prevents vibration. The case |30a can be placed as most convenient for connection to the lead screw, but the case |30 should be so placed as to permit the drive shaft to be in a vertical position at about midway of the carriage movement.

The arrangement shown of the miter gear drive of the cross feed screw through the telescoping shaft, permits .of free sliding movement of the carriage without effecting the cross slide.

The roller clutch units Operating the lead screw and the cross feed screw, are shown in detail in Figures 3, 4, 5, 6, 8, and 9, and comprise a supporting base frame |34 in which a crank shaft |36 may rotate inv ball bearings |01 (Figure `8) which are secured by bearing caps |30. i

The shaft carries a pulley |39 which is driven by a. motor |40 supported by a hinged bracket |4| in the lower part of the foundation case, as shown in Figure 2.

The shaft has a small crank throw |42 on which a connecting rod |43 is secured to give the reciprocating motion to the clutch.

The lower end of the connecting rod is provided with a bearing boss through which extends a bearing pin IM to connect with an end of a walking-beam |45.

The opposite end of the walking beam is hinged to an arm |06, Figures 3, 5, and 6,'by a bearing pin |01.

The beam has internal slide surfaces |58, Figures 5 and 6, on which a slide block |50 is free to move. This block has its bearing on a pin which extends through openings |52 in the sides of the beam and also through upward extending projections |54 of a variable leverage slide |55, Figures 3, 5, 6, and 8 slidingly secured to the supporting 'frame by a plate |58 (Figure 8) at one side, and by a pump base |58, at the other.

The arm |48 is flexibly secured to a clutch sleeve |59 by a stud |60 inserted therein (Figures 3, 4, 5, and 6) which extends through a control plate ISI, the arm |66, and through a stili coiled spring |63. These are all secured together by an adjusting nut |64 to form a rockable resilient drive connection by which' the rotative speed -of the clutch shaft is reduced in response to the lncrease of load placed upon it. The control plate |6| is provided with opposite control ends SI5 and SIB, Figures 5, 6. and 7, which determine the relative pressure before yielding. By varying the distance of these ends from the central 'opening 8H, the pressure in opposite feed directions may be Varied. The yielding pressure is determined by the spring |83 (which may be of any modulation), adjusted by the nut |60.v

The sleeve |59 is carried on the clutch shaft vby heavy roller bearings at either end of the sleeve (Figure 4) to give rigid support to an oscil I lating clutch member |65 formed integral with 7 |1| in; which' a hardened outer clutch ring |13 (Figur' s 4, 11, and 12) is rigidly held by a screw cap Hg, Figures 3, 4, and 9.

The clutch ring |18 has eight internal clutch depressions formed into driving faces and |19 (Figures 11 and 12) of a curved form having about thirteen times the radial distance indicated at |80 (Figure 1l) that the radial point is at one side of the clutch' center, as indicated at |8I.

This face form gives a positive drive upon roller contact, but releases without sticking upon re versal of the drive.

The flange |12 is pierced with four openings |83, Figure 4, through which extend four studs |04 integral with a roller cage |85, Figures 4, 10, 11, and 12, to support and to operate the cage.

This cage is in th'e form of a light cylindrical sleeve operating between the clutch member |65 and the dutch ring |13. 1t is pierced with eight slots |88, Figures 10, 1l, and 12, in which eight rollers |90, Figures 4, 11, and 12, are free to move sidewise to a limited extent.

'I'he rollers are drilled lengthwise and carry a pin |9| having a rounded outer end, Figure 4, in either end pressed outward by a compressed spring |92.

When the rollers are in their assembled position, the outer end of the pin engages in a groove |94 in either end of the cage that has faces inclined both toward the roller and also in the sidewise directions as shown in Figure 10. 'I'h'e spring pressure then acts to maintain contact of roller and clutch ring at all times, and also acts to keep the roller in its central position when not deiiected therefrom by pressures greater than a1- lowed by the spring. The spring action also provides for uniform pressure on all rollers and at both ends of the roller, when in driving contact.

The cage is deflected sidewise from its inoperative position (Figure 11) to move the rollers to their driving position shown in Figure 12, by the following mechanism:

The outerv end of the studs |84 extend through and are removably secured to a flange |96 at one end of a sleeve |91, Figures 4, 9 and 10, which is closely held against endwise movement but is free to oscillate on the clutch shaft, by ball bearings 98 at either end of the sleeve.

The bearings are without cage and are supported by a ilxed,race200 and by an adjustable race Figure 4.

A clutch control sleeve 203 slides endwise on the sleeve |91 but is prevented from oscillating thereon by two driver pins 204 fixed in a flange 205 of the sleeve 203 and freely slidable in the flange |96, as shown in Figures 3, 4 and 10.

The opposite end of the sleeve 203 has a helical extension 206 (Figures 3, 4, and 10) which engage with a matching helical driver plate 201 (Figures 3 and 4). This driver plate is locked to the clutch shaft by a key 208 (Figure 4) and is held endwise by a nut 209 (Figure 3), which h'olds the assembly together.

A thin washer 2|0 (Figure 4) aids in adjustment of the parts. The above arrangement allows end movement of the sleeve 203 to rotate the cage relative to the clutch ring t0 move the rollers into operative contact. The movement of the sleeve 203 is obtained by the following mechanism. A

The sleeve 203 has an operating flange 2|2, Figures 3, 4, 9, and 10, which engages with two control forks 2|3 having matching plates 2 secured on the opposite side of the operating flange to allow close control during rotary motion of 8 the flange. Positive endwise movement in either direction is provided by two shifter forks 2|4 (Figures 3, 4, and 9), which carry pins 2 Il having bearings in the control forks.

The opposite ends of the shifter forks are rigidly fixed to a sleeve 2|0 (Figures 3, 8. 9, 13, and 14) which is free to oscillate on a stud 2|1, Figures 8 and 9, ,fixed vertically in a base plate 2|8 which is secured to the frame |34.

'I'he sleeve 2|6 is provided with a vertical flat driving surface 2|9 (Figures 13 and 14) against which a flange retained matching surface 220 of a hook-up arm 22| is forced by a spring 222 (Figures 8, 13, and 14), the pressure of which is adjusted by a nut 223 on a, stud 224 xed in the sleeve.

'Ih'is provides a yieldable drive for thev clutch cage.

The outer end 226 of the hook-up arm is moved sidewise upon contact with either of two hook-up levers 221 and 228 to force the clutch rollers into operative contact. This is done by the following mechanism.

The hook-up levers are freely pivoted in individual slots in a carrier h'ead 230 by a bolt 23| (Figures 3, 9, 13, and 14) and are separated enough to permit of individual action without interference. The lever 221 is provided with an operating arm 229 and also with a counterbal ancing arm 225, while the lever 220 is provided with an operating arm 250 and a counterbalancing arm 249.

The carrier head is rigidly fixed to the upper end of a lever 233 (Figures 8, 9, and 13) which is pivoted by a pin 234 to the base plate 2|8(Figures 8 and 9) to oscillate thereon.

The fupper end of the lever is also fixed to a driving fork 235 having an adjustable fork plate 236 secured thereto by bolts.

This fork drive contacts either side of an eccentric cam 238 on the power crank shaft to oscillate the carrier head.

The hook-up levers are controlled, electrically, by square wound coils 240 and 24| (Figures 3, 8, and 15) operating with' square laminated cores 242 fixed to a coil supporting frame 243 which is fixed to the base plate 2 I8. Two armature levers 244 and 245 are freely pivoted to the coil frame by a pin 246 and are each provided with an extended end formed into a fork 248 t0 engage the respective operating arm of its hook-up lever.

The armatures are retracted by adjustable springs 25| and this movement is limited by stop screws 252, Figures 8 and 15. 1

It will be here noted that all parts having reciprocating motion, or being subject to movement from rest, should be made as light as possible to prevent Wear, to prevent sound upon contacting stationary control parts, and also to allow of the greatest operating speed.

Where possible, all reciprocating parts should be hardened to reduce the contact surface re quired to obtain reduced size of parts and still maintain endurance of the mechanism. The clutch mechanism is anv improvement on that shown in my co-pending application, Ser. No. 330,525, and operates as follows.

The power vdriven crank shaft |36, the connecting rod |43, the walking beam |45, the arm |46, the clutch sleeve |59, and the pressure control mechanism comprising, the control plate I6 the spring |63, and the adjusting nut |64, to'

gether with their bearings and supports, constitute the driving mechanism of the clutch.

The maximum degree of oscillation of the clutch sleeve for any crank throw is determined by the position of the slide block |55 which controls the leverage of the walking beam, and is obtained only when the arm is-held by the spring against the upper surface of the control plate during the complete revolution of ,the crank shaft (Fig. Any resistance to movement of the clutch sleeve, great enough to overcome the pressure of the spring, will permit the arm to pivot noiselessly on one end of the control plate during a portion of the revolution and the oscillation of the clutch sleeve will be reduced in extent, or be completely stopped if the resistance be great enough. This action is shown in Figure 6. y

'Ihe clutch roller springs |92 act to force the rollers outward relative to the cage and into contact with the clutch faces |18 and |19 of the clutch ring |13. These are inclined toward each other and react to move the cage to its central position (Figure 11). In this position, the rollers are held away from the clutch sleeve about two one-thousandths of an inch and the sleeve may i freely oscillate without clutch action.

The hook-up arm 22| is operatively connected to the cage by the mechanism shown and is normally held in a central position in common with the cage. Side deflection of this arm in one direction will result in clutch engagement to rotate the clutch shaft |3| in one direction, while deilection in the opposite direction will result in clutch engagement for the opposite direction of rotation.

The clutch rollers should all be in driving contactwith the clutch sleeve at the start of its oscillating movement to insure noiseless action, and eflicient drive.

As the hook-up arm 22| drives through' the spring 222, the inertia of the cage and connected parts will prevent the rollers from contacting as early as with a positive drive, and the timing of the reciprocation of the carrier head 230, relative to the power movement of the clutch sleeve, must be advanced to correspond to th'e speed of the crank shaft, which is about 2000 R. P. M. in the usual application. In practice it has been found desirable to advance the timing of the clutch engagement to a point slightly earlier than the start of the power movement of the clutch' sleeve. Any slight variation in timing may be then obtained by adjustment of the spring 222.

When the armature 244 is deected bythe electrical action of the coil 24|, or by mechanical depression of the lever 5| 0a, the very light hook-up lever 221 is swung outward in the carrier head by means of the sliding engagement of th'e armature fork with the arm 229. The spacing of the hook-up levers 221 and 228, and the width of the contact end of the arm 22| (Fig. 14) are such as to permit the hook-up levers to swing beyond the engaging point of the arm for movement in one direction only.

UpGn engagement with the hook-up lever 221, the hook-up arm will be forced, by rotation of the crank shaft, to move the clutch rollers into driving contact in the direction controlled by the armature 244. Continued rotation of the crank shaft th'en starts the clutch sleeve on its power movement and the clutch shaft |3| will be rotated until the end of the movement, as the rollers are held in contact until the driving movement is completed. Upon reversal of the clutch sleeve, the rollers will be automatically released and the roller actuating parts will be returned t0 their central position by means of th'e roller springs. The cycle of clutch action is now complete, and

' Sure.

will be repeated as long as the armature 244 is deflected. If, however, the armature 245 be deilected, the hook-up lever 221 will move the rollers for contact in the opposite direction and the rotation of the clutch shaft will be reversed.

The armatures 244 and 245, of both' control units, are electrically operated by a tracer which is shown in detail in Figures 28, 29, 30, 31, 32, 33, 34, 35, and 36, and the protective cover 255 of which is shown in Figures 1, 2, and 29.`

A base 256, Figures 28, 29, and 30, is provided with upward extending side plates 251 and 258, Figures 28, 29, 30, and 34, through which pivot screws 259 extend to pivotly support a nger Plate 26 0. This plate is provided withl an extended contact arm 26| which is insulated from the plate.

The plate is retracted in an upward direction by a tension spring 263 (Figures 29 and 30) and is provided with a control depression 264 in its upper surface (Figures 29, 31, and 34) in which the lower end of a control linger 265, Figures 29 and 34, acts to operate the tracer contacts.

The control finger is adjustably locked' in a tracer bar 266 by a nut 261 as shown in Figures- 21|, and the tracer bar is freey to swing on its pivot supports in' any direction. This provides against damage to the tracer by forcible contact with the templet.

A ring 213, Figures 29, 31 and 34, is cut in the finger plate concentric with the control depression. This ring is deeper than the control depression to; permit .the control circuits to be broken when the tracer linger is moved to enter it by excessive movement of the tracer bar.

The outer enclv of the control linger carries an upward movement contact 215, Figures 30 and 32, that may contact with a contact point on a spring control lever 216 serving to control the feed of the tool in the direction of an arrow 6| of Figure 1, hereafter known as the infeed.

The spring lever 216 is supported at its opposite end by insulating blocks 211 and 218, from the base.

A downward moving contact 280, Figures 28, 29, and 32, is carried at the outer end of the control finger to contact a control lever 28| to control the cross slide movements opposite to the arrow 6| hereafter known as the out-feed.

This lever is secured by insulating blocks and 283.

These blocks also support a control lever 284, Figures 28, 29, 30, and 32, which is of greater length thanI the lever 28| and is provided with a contact to meet the lower end of an adjustable contact screw 285 which extends through an insulating block 29| xed to the base. 'I'his lever carries a driver connection comprising an encircling plate 286 (Figures 28, and 33) insulated therefrom by a thin wrapping 29|) (Figures 28 and 33) and secured to the lever by pres- This plate has two points, 281 and 288 which extend on either side of the lever 28| with a clearance which determines the feed overlap of out-feed and carriage circuits.

A contact lever 293, of the same construction as 284 (Figures 28, 30, and 32), is supported by the blocks 211 and 218 and contacts with the upper end of an insulated contact screw 294 supported by the base.

Thelever 293 is also provided with an insulated driver 286 of the construction asused to operate the control lever 216.

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