US1143948A - Control system for gun-mountings and other mechanism. - Google Patents

Description

A. T. DAWSON @L 1. HORNE.

CONTROL SYSTEM FOB GUN MOUNTTNGS AND OTHER MECHANTSM.

APPLICATION PuiMun/12.1912.

1,143,948. Patented June 22, 1915.

UNITED STATES PATENT GFFCE.

ARTHUR TREVOR DAWSON, 0F WESTMINSTER, LONDON, AND JAMES HORNE, F BARBO-W-lN-FURNESS, ENGLAND, ASSIGNORS TO VICKERS LIMITED, OF WEST- MINSTER, ENGLAND.

kCONTROL SYSTEM FOR GUN-MOUNTINGS AND OTHER MECHANISM.

Specification of Letters Patent.

Patented June 22,1915.

Application filed July12, 1912. Serial No. 708,964.

T0 fri/ 112710112 it Tray concern Bc it known that we,- ARTHUR TREvoR Dawson', knight, and JMns HORNE, both subjects of the King ot' Great Britain, residing, respectively, at Vickers House, Broadway, 'estminster, in the county of London,liugland, and INaval Construction Work, lla rro\v-i1i-l `urness, in the county of Lancaster, England, have invented certain new and useful Improvements in or Relating to Control Systems for Gun-Mountings and other Mechanism, of which the following is a specification.

This invention relates to control systems for gun monntings and other mechanism.

.In control systems hunting gear has been employed in conjunction with a power driven member forming part of the mechanism to be driven, and with a member which is actuated electrically from a distance but is incapable of itself exerting any appreciable force beyond that which is necessary to operate a rela-y for bringing the motivevpower into action. lrVhen the electrically actuated member is moved out of alinement or coincidence with a neutral point on theother or power driven member, an electric circuit is closed through suitably arranged contacts forming,l part of the two members and energizes the relay which brings into operation a motor for driving the mechanism a-nd the said power driven member, such operation continuing so long as the circuit remains closed, z'. e., until the neutral point of the power driven member regains its position of alinement or coincidence with the electrically actuated member.

According to this invention the aforesaid members are so constructed and arranged that when, on the completion of an electric circuit through the aforesaid contacts, the relay moves the valve, rheostat or lother control device appertaining tothe motor of the mechanism to be driven, the relay will at the same time open the electric circuit and thus stop its vown movement, the extent of the relay movement required to thus break the circuit depending on the amount of displacement or lag created between the power driven member and theelectrically actuated member. Conversely as the two members move into realinement the electric circuit through the relay will-again be closed and the relay will move inthe opposite direction and will gradually shut ol'l' the power tothe motor driving the mechanism as the position of coincidence between the members, is approached, so that when this position is reached the supply of power will be quite cut oli by the relay. Thisinteidependence of the movement of the relay and the relative displacement of the electri cally actuated member and the power driven member insures that the starting and stop-- ping of the motor will take place in a gentle manner and without undue oscillation of the control device when the aforesaid mem bers assume their position of coincidencev or neutrality to bring the moto/'r to rest. F or this purpose the contact surfaces of the power driven member are separated from each other by a suitably inclined' or curved insulating strip or gap and the contact on the electrically actuated member is caused to be displaced laterally by the action of a relay when movement is imparted to the said member from. the transmitting station, the extent of the lateral displacement depending on the degree of movement transmitted to the control device by the relay. By these means the amplitude of movement given to the control device and the length of time expiring before the said device resumes its normal position are proportional to the relative displacement or lag that exists between the two members.

Where the power which the electrically actuated member is capable of exerting is sufficient, the inclined or curved insulating strip or gap on the drum may be replaced by a cam groove of similar shape in which a pin or roller on the end of thel electrically actuated member is adapted to engage. The movements of the controlling gear would 4then be in exact accordance with the path as turret training and gun elevating mechanism, it is often necesasry that the said gear shall be displaced from the position it has received from the transmittingstation in order to correct the displacements for such conditions as the `varying muzzle velocities of the gun, and in the case of training^mechanism to correct the displacements for the separation or distance of the gun Afrom its distant sighting station.

In order that'these corrections may be effected in an improvedmanner, we provide means for displacing the motor or other operating device of the electrically actuated in ember about the axis of rotation of the said member. For this purpose the motor or other operating device of the. electrically actuated member 1s mounted on a frame thatcan be angularly displaced about the axis -20 of rotation of the electrically actuated memi ber and the power vdriven member. By fix- .ing 'a pointer to the frame we can set the latter at any point on a scale engraved in terms -of the particular correction we wish' to apply. We may if desired employ other means for swinging the frame carrying the motor of the electrically actuated member, about the axis of rotation of the said member.

In order that the said invention may be clearly understood and readily carried int-o' v,effect we will describe the same more fully withv reference to the vaccompanying draw.'-l

in s, in which igure 1 is a sectional elevation showing one constructional form of the apparatus embodying ourvinvention. Fig. 2 is a detached view ofthe power driven member,

showing a modified arrangement of the con- 40 tact surfaces thereon. Fig. 3 is a view simi-` lar toFig. 1, showing a modified form of apparatus for enabling the electrically actuated member to make more than one revolution with respect to the power driven mem- ,45 ber. Fig, 4 is an elevation showinga modified form of apparatus, that is used when tw receiving step-by-step motors or other op" ating devices are employed for working .theielectrically actuated member. Fig. 5 is 'r'sectional` elevation showing a modified form of the apparatus illustrated in Fig. 4.

Fig vis a diagram showing the electrical connections of the arrangement illustrated in Fig.. 5. Fig. 7 is also la view similar to Fig. 1 showing a convenient arrangement of the motor mounted on. an angularly displaceable frame. a

In all these figures like letters of reference indicate similar parts.

.A is the power driven member, B the electrically actuated member which is shown as being driven by a step-by-step electric motor B operated from the transmitting station, and C the control device of the mololl" used for driving the mechanism, the

-the power driven'member A is in the .form

` mitting station.

ranged co-axially-within-the shaft AX and said motor being inthe examples illustrated intended to be driven by hydraulic power.

a represents the insulating strip or gap separating the contact surfaces a', a? on the power driven member A, and b", bx represent the contacts forming part of the metalA contact plate or bridge piece b on the electrically actuated member B.

In the examples shown in Figs. 1 to 4 of a drum provided on its periphery with the contact surfaces a', a2 which comprise rings or strips of metal so'formed -that a part of the insulating gap a between them is at anv inclination .to a circumferential line lon the drum.. The said drum is mounted on a shaft Ax having a pinion- A which forms part of the gearing connected to the mechanism to be driven, which may be the elevating or training gear of a gun, the said pinion A being `driven by the hydraulic motor. The peripheryvof the said drum is furnished, in addition to the aforesaid two contact rings a', a2, with a third ring a3 for supplying current to they contact bx; the 9.0 other contact bX is adapted to bear upon either of the rings a', a2 or upon the insulated gap a as will be hereinafter described. The electrically actuated member B is mounted on a splndle B driven through a spur wheel b engaging with an elongated pinion b2 on the shaft of the step-bystep motor Bx which is actuated from the trans- The said spindle is aris adapted tolmove axially as well as re- ?volve, and when, as is intended in the example shown, anhydraulic motor is used for driving the mechanism, this spindle is 4connected by meansof an oscillatory lever C to the stem of al control valve (constituting the aforesaid control device C) for the hy-4 draulic motor. The said lever oscillates about a pivot 0 which is adjustable in a slot in the lever so that -the ratio ofmovement between vthespindle B and the con# trol C can be varied if desired.

Referring more particularly to Fig. l, each of therings a', a", a3 on the drum A is electrically connected with slip rings a, a-ZX, ai on the rear face of the'drum, of. which a, a2* are connected to'two electromagnets or solenoid coils D D constituting, with a plug valve f3 operated thereby, the aforesaid relay for causing 'the control valve C to be moved. The ring as* is connected to the source of electric supply. The said magnets or coils, 'when energized. operate an armature or core D", the direction of movef ment of which depends upon the particular 125 contact ring with which the contact b* is in electrical connection. The said armature or core is shown as formed with rack teeththat gear with a pinion on the spindle Sd of the,

Plug

which is dispoed a ram ff formed on the stem l," at the omtrol valve the end of' the cylinder marest the valve C being supplied with motive fluid under constant pressure. 1n acci rdance with tlie direction in which the armature or core is displaced by the magnets or coils, the plug valve tl is moved to place the rear end of the cylinder to pressure o1' to exhaust, thereby causing a movement in one or other direction of the ram c on the stem of thc control valve C, and moving the latter to admit pressure fluid to the motor for driving the elevating or training mechanism and the aforesaid drum A.

The aforesaid neutral point of the insulating gap a. is in the center of the inclined portion thereof. and when the contact JX bears upon this point (as shown in the figures) the parts are at rest with the gun elevated or trained to a position corresponding 4to the elevation or training angle transmitted to the step-bystep motor B". Vhen the electrically actuated member B is angularly displaced from the transmitting station as aforesaid its contact b" is moved fromthe said neutral position on to one or other of the two Contact rings a', `U2 of the drum A according to the direction of movement imparted to it; assuming that the said member is moved to place the contact /X on the ring a. the solenoid D is accordingly energized, and the plug valve d moved so that the space on'the right of the ram c' is placed to pressure, with the result that the control valve "C is displaced longitudinally toward the left and admits fluid pressure to the hydraulic motor for driving it in the required direction. r1`his movement of the valve C longitudinally displaces the spindle B of the electrically actuated member to the right through the lever C. with the result that the said member and its contact are shifted transversely to the drum A in the opposite direction to ilie opening movement of the control valve.

The electrically actuated member B is intended. in actual practice, never to be any considerable angular distance in advance of the neutral point (z'. e. the center of the inclined portion of the gap a) of the drum A. and the said memLer does not therefore become angularly displaced to a position be-v vond the ends of the inclined portion of they insulating gap a.' consequently within these limits the amount of movement given to the con-trol valve t is in proportion to the relative displacement or lag between the member B and the drum A as aforesaid. Outside these limits however the valve is always completely opened.

The transverse movement of the electrically actuated member dees not move the Contact 7)* out of engagement with the ring u? but returns the contact. b* to the insulating strip or gap 'the supply of current to the solenoid l) of the relay is then immediately cut oil' and the aforesaid plug valve d' is centertw'l bv suitable means. such as springs acting i n the toothed armature or Acore l)x ot tlnl solenoids. and the control valve C is thus retained in the open position to which it has been moved. 'l`he hydraulic motor thus set in motion and at the `same time imparts angular movement to the drum A thereby bringing the other contact ring a beneath the contact .7). The other solenoid D of the relay is then energized and the plug valve 1l actuated in the opposite direction to that aforesaid. with the result that the space on the right ot' the ram c is placed to exhaust so that the fluid pressure constantly acting in the space at the left of the ram operates to move thc control valve C to the right. 'e'. e., toward its closed position, this movement continuing (without however being of sufficient extent to effect the closing of the control valve and consequently without stopping the movement of the drum A) until the contact b* has been returned transversely to a positionon the inclined portion ofthe insulating strip or gap a.

The further movement ot' the drum again brings the contact ring a beneath the contact 72'* and through the intervention of the solenoid D of the relay again moves the plug valve (Z into :1 -position to open the space on the right of' the ram c to exhaust. The control valve is thus caused to again move toward the right (i. e. toward its closing position) and in so doing causes the contact /X to again bear upon the insulating gap fr. The further movement of the valve is thus prevented in the manner already described. These successive increments of movement of the contiol valve toward the closing position are continued until the contact reaches the center or neutral point of the aforesaid inclined portion of thc in sulating strip or gap 0 whereupon the valvel is completely closed and the motor is finally brought to rest without any reversalY and consequently without any oscillatory movement of the hydraulic motor and the elevating or traininggear. The path traced on the drum by the contact Z/X is an indulating curve or zigzag line the mean 4of which is a line parallel to 4t'ne insulating strip or gap.

ly suitably varying the degree of inclination of the inclined portion of the insulated strip or gap a. the valve may be caused to move any desired amount for a particular extent of lag or displacement `between the two members.y the valve movement varying in accordance with the inclination of the said gap. Thus with a gap which is only slightly inclined to a circumferential line on the drum. the valve movement in relation to the lag is smaller laxis of the. drum A, the inclination being in the same direction as that ofthe main inclined portion of the gap a. LBy this means when the contact bx is angularly displaced it will quickly reach the contact ring a or a2 (according to the direction of movement) and thus cause a quick movement of the valve C from the central position to occur and at once takeup the lap of the valve.

'Fig 3 shows y,a constructional form of the 'invention in which the electrically actuated member B is adapted to make more than one revolution relatively to the drum A. In this'example weprovide a second or auxiliary drum AO that is driven at a slower speed than the drum A, by means of toothed rings a, ao on the drums A, A respectively and interposed toothed wheels a"x aoc. We also provide. an auxiliary electrically actuated member Bo on a spindle?)o disposed within the spindle B Aof the main electrically actuated member B, the said spindle b being driven at ap reduced speed by means of toothed vwheels from the spindle' B. The said auxiliary member BG has two contacts BQ", B0X, the former of which is adapted to bear against one or the other of two insulated contact pieces a0', a02 on the auxiliary drum Ao or against an insulating gap between them, and the other BO* against the aforesaid supply ring a3 of the drum A. The said contact pieces a0', a02 are connected to insulated slip rings ao4 respectively, which are in circuit with the aforesaid solenoids D', D as shown. When the contact /X lies on the center or neutral point of the inclined part of the .insulating gap a the contact B00 of the auxiliary `member Bo lies on the insulating ga between the two contact pieces ao, a02. en "the amount of relative angular displacement or lag between the electrically actuated member B and the drum A exceeds a certain amount, the contact pieces ao', af, onv

the slow auxiliary drum AO operate to maintain the supply of current to the particular solenoid that has previously been energized through the intervention of the drum A and the contact 71'* of the electrically actucontact pieces a, a" which then maintains the sup ly of current to one or other of the solenoids D D as aforesaid. The shape of the-contact rings a a is such that if the member B makes a half revolution to-either side of the central portion of the gap a, the contact b* ,would .pass from whichever ofthe rings a', a it was bearing against Iinto contact with the other ring.

In order to prevent this last mentioned contact ring supplying current to the nonenergized solenoid when the electrically actuated member B has made half a revolution relatively to the said drum as above stated, the spindle d of the aforesaid plug valve d is, in the example lshown, provided with a rotary switch da that automaticallyY breaks the circuit between the non-energized solenoid and its contact ring on the drum A. By this means after a certain amount of lag has taken place'the control of the energizedv solenoid rests with the auxiliary drum A and the auxiliary member B0, the drum A and its electrically actuated mem-` ber B only coming into action when the auxiliary drum nd its member have been brought into approximate alinement, z'. e., returned to the fposition in which the contact BQ? just rests onA the insulating gap between the contact pieces ao', a02. The drum A and its member B then take over the control of the solenoid and finally become alined, i. e., the contact b* reaches the central or neutral point of the inclined portion of the gap a as above described, and the mechanism comes to rest 'with the-contact BOO resting on the center of thegap between the contact pieces of the drum A".

In the example shown in Fig. 4 two switches (one of which transmits large increments of range or bearing as set forth for example A in the specification of the British Patent No.

' 11019 of 1911) are used at the transmitting station, and two motors B", BX", at the receiving station, connected to the spindles of the members B, B". Of these the motor BX* and the member B appertain to the switch transmitting the larger increments. In this arrangement no gearing is employed between the members B, Bo, as the ratio of the movement of the motors is the same as that of the transmitting switches.

In the foregoing arrangements the controlvalve C, the hydraulic cylinder d2 and its plug d may be replaced by a control switch and solenoid where the elevating or training gear is driven by electric power.

Although we have described the contact rings or strips as being on the periphery of a drum, they might obviously be on the face of a disk replacing the drum, the insulating gap between the said contact rings being arranged at an angle to a radius of the disk. The contact on thc electrically actuated member would in this construction be moved las radially in accordance with the movement of the control valve or control switch.

ll'hen two electric motors are employed as in the last precedingl arrangement, instead ot using two separate drums and two electrically actuated members as hei-einbe- `ore described, we may, as. shown in Figs. 5 and j employ a single drum o r disk A and two electricallyl actuated'membcrs B, Bo moving at different speeds, the slower membe2.'` BO being driven through .a form of cpicyclic gear` by its step-by-step motor 13"". Tfhen the gun is being trained or elevated slowly the two step-by-step motors angulai-ly displace the spindle bo carrying the directly actuated or fasteijmcinber B, and also displace the outer spindle' B on whichI is formed the sun wheel if" of the epicyclic gear. 4lllien the gun is being elevated or trained quickly the step-bystep motor -B"" geared to the outer spindle B formed with the sun wheel b2* (which motor apperta'ins to the transmitting 'switch that 'isradapted to transmit large increments of range or bearing) `alone moves and causes a displacement of the slower member BO which in turn causes the hereinbefore described relay to operate and cause the drinn A to be angularly displaced an amount corresponding to that of the sun wheel b2". In this construction segments are formcdin two circles on the face .otthe drum it. The outer circle of segments c c?, a, aT and as appertains to the Contact b" of the member B and the inner circle a4, a5 appertains to the contact BOD of the member B0. The contacts and BO" of the members'B and BO Yrespectively bear`` against a supply spective-ly connected toI the solenoids D, D.

The said segments a, da, at', a5, a, al and a8 are in electrical connection with lingers a"",'

alnx, ab, axx, aGxx7 a7x and axx l.espec tively, that are adaptedto engage with the contact plates GEC. The supply ring a3 is connccted'to the source of electric sup Plyspect to the, drum A it causes for example the segment a6 to be electrically connected withthe supply ring a3. The solenoidv D will accordingly be energized, and the valve C will be moved as hereinbefore described until the finger am appertaining to the segment is cornes opposite the gap between the two contact plates C", 'C"". As the drum A moves to assume its original or neutral position with respect to the member B and the contact.- rrs Abecomes electriiied, the vrllve will move until the gap between the plates f", C rests upon the corresponding contact and will then be completely shut ott' and the parts brought to rest. By a lVhen the member B moves with re-V thepreviously described arrangement with a laterally displaceable Contact, but is more intermittent in character owing to the -number of partial opening and closingI movements or" the control valve being limited to the number of contact segments. only one motor is used as is Ithe case in the construction shown in Fig. l themember B and its circle of segments need not be employed. In this case the teeth of the wheel b2" are formed on the spindle bo 'carryingthe member B. v

Instead of the hydraulic cylinder relaiv illustrated in Fig; l we may employ other suitable convenient- -tcrms ot valve opening mechanism the connection ot thesaid mechanism to the contacts on the dial of the drum of the power drii'en member vbein similar to that above described.

Fi g. 'i' shows a constructional form of the means for displacing the motor o B"`in order to malte the necessary corrections 'in the setting of. the member B for varying muzzle velocity or for the separation or distance of the gun from its distant sighting station.l

AThe motor B"l is mounted on a frame E carried by a bearing IQ" co-axially with' the spindle B and the'drum A. The said frame is provided with a pointer @and the bearing E has gradua'tions as shown; bydisplacing the trame until the pointer e comes opposite the desired graduation the required correction is made. The construction shown in Fig. 7 is, in other' respects, similar to that of Fig. o

rlhe modification shown in Figs. 5 and 6 ot' the drawings forms the subject matter of a divisional application, Serial No. $011,165, filed'December 2, 19l3. A

ll'hat weclaim and desire to secure by Letters Patent of the United States is l. In a con-trol's'vstem forvpower driven mechanism, the combination of amember driven from said mechanism, armember actuated from a. distance, a relay under the control of said members, a control device for the power' driven mechanism, means for" operating said control device from the relay, means whereby relative movement between said membersrenders the relay operative, and means whereby the movement of said relay consequent on its being rendered operative, renders it again inoperatii e, the

amount of such relay movement varying according to the relative displacement between the two members.

2. In a control system for power driven mechanism, the combination of a member driven from said mechanism, contacts form- When ing part of said member, a relay in elec trical connection with saidcontacts, a member actuated from a distance, a control de vice for the power driven'mechanism, means for operating said control device from the relay, means whereby relative movement between said members completes the electric .circuit through the relay, andmeans whereby the movement of the relay consequent on 1u the .completionl of the circuit, eiccts the opening of the circuit, the amount of such relayv movement varying according to the elative displacement between the two mein ers.

3. Ina control system for powerdriven mechanism, the! combination of a member driven from'said mechanism, contacts torming part of said member, a relay in electrical connection with said contacts, a member ac# jtuated from a distance, a control device for v.the power driven mechanism, means for operating said'control device from the relay,

y means whereby relative movement between said members completes the electric circuit 2 5 through the relay, andmeans whereby the movement of the relay consequent opl-'the completion of the circuit, causes relative `movement between the two members to take `place in a direction lateral tov the movement of the second mentioned member when actuated from a distance, this relative lateral. movement effecting the opening of the circuit through the relay. y 4. In a' control system for power driven mechanism, the combination of a member driven from said mechanism, contacts forming part of said member, an inclined gap between said contacts, a relay in electrical con' nection with said. contacts, a member actu- 0 ated from a distance, a control device for the power driven mechanism, means for -operating Vsaid control devicel from the relay, means whereby, the movement of the Vsecond mentioned member out of contact with the insu- 4 lating gap as a result of the relative displacement between said members completes the electric circuit through the relay, and means whereby the movement of the relay consequent on the completion of the circuit, causes the said second mentioned member to 'be returned into,contact with the insulating gap to open the circuit through the rela 5.yIn a control system for power driven mechanism, the combination of a rotary member driven from said mechanism, contacts forming part of said rotary member, an inclined insulating gap between said contacts, a relay in electrical connectionwith said contacts, a rotary member actuated from 'a distance, a control device for'the power` driven mechanism, means for operating said control device from the relay, means whereby the movement of the second men# tioned member out of Contact with the in'- sulating gap as a result of the relative disa" placement Ybetween said rotary members completes the electric circuit through 4 "the relay, and means whereby the movement of the relay consequent on the completion of the circuit causes the said second mentioned member to belreturned into contact with the insulating gap to open the circuit through the relay. i

6. In a control system for power driven mechanism, the combination of a member driven-from said mechanism, contacts forming part of said member, a relay in electrical' connection with said contacts, a member ac-v tuated fromA a distance, a: hydraulic control device for said power driven mechanism a. hydraulic actuating device for said control device, means forming part of said relayvfor causing said actuating device to become operative, means whereby relative movement between said members completes theelectric circuit through the relay, and means where.- by the movementof the relay consequent on the completion of the circuit. effects the pening of the circuit through the relay. Y 7.In a control system for power driven mechanism, the combination of a drum drivennhereby, contacts-on said drum having an inclined insulating gap between them, a relay in electrical connection lwith said 9 contacts, a member actuated from a distance,

'a hydraulic control device for saidpower driven mechanism, aI ,hydraulic actuating device for said control device, means forming part of said relay for causing said actu- 10,0 ating device to become operative, meansA whereby the movement ofthe member out of contact with the insulating gap as a result of the relative displacement between said member and drum completes 4the electric cir- 105 cuit through the relay. and means whereby the movement of the relay consequent on the complet-ion of the circuit, eii'ects the opening of the circuit through the relay by returning v the said member into contact with the insulating gap. 8. In a control system for power drivenl mechanism, the combination of' a drum driven thereby, contacts on said drum having an inclinedinsulating gap between them, 1,15 a relay in electrical connection-with said contacts, a motor .controlled from a distance, a member actuated, by said motor, a hyn draulic control device for said power driven. mechanism, a hydraulic actuating device for said control device, means forming part of said relay for causing said actuating device to become operative, means whereby the movement of thesaid member out. of contact with the insulating gap as a result of the relative displacement between said member and drum completes the electric vcircuit through the relay, and means wherebyl the movement of the relay consequent on the v 1cem'pletion, of the circuit, effects the opening 130 of the circuit through the relay by returning the said member into contact with the inclined .insulating gap.

9. In a control system for power driven mechanism, the combination of a drum driven thereby, two contact rings and a supply ring on said drum, an inclined insulating gap between said contact rings, a relay in electrical connection with said contacts, a motor' controlled from a distance, a member actuated by said motor, Itwo contacts on said member one of which is in constant engagef ment with said supply ring, a hydraulic control device for said power driven mechanism, a hydraulic actuating device for said control device, and means forming part of said relay for cau-sing said actuating device to become operative.

10. In a control system for power driven mechanism, the combination of a main member driven thereby, an auxiliary member driven at a dilferent speed, a main member actuated from a distant station, an auxiliary member actuated thereby at a different speed, a relay under the control of said members, a control device for the power driven mechanism, means for operating said control device from the relay, means whereby rela.- tive movement between said members rer.- ders the relay operative, and means whereby the movement of said relay consequent on its being rendered operative, renders it again inoperative.

1l. In a control system for power driven mechanism, the combination of a main member driven thereby, an auxiliary member driven at a dilterent speed, contacts forming part of said members, a relay in electrical connection with said contacts, a main member actuated from a distant station, an auxiliary member actuated thereby at a different speed, a control device for the power driven mechanism, means for operating said control device from the relay, means whereby relative movement between said main members completes the circuit through the relay, means whereby the auxiliary members maintain the circuit after the relative displacement of the main members reaches a certain amount, and means whereby-the movemen-t of the relay efects the opening of the circuit through the relay.

v12. In a control system for power driven mechanism, the combination of a'main drum driven thereby, an auxiliary drumvdriven at a different speed, contacts forming part of said drums, a relay in electrical connection with said contacts, a main member actuated from a distant station, an auxiliary member actuated thereby at a different speed, a control device for the power driven mechanism, means for operating said control device from the relay, means whereby relative movement between sai-d main drum and main member completes the circuit through the relay, means whereby the auxiliary drum and auxiliary'meinber maintain the circuit closed after the relative displacement of the main drum and member reaches a certain amount, and means whereby the-movement of the relay effects the opening of the circuit through the relay.

In' testimony whereof we a'lix our signa-v tures in presence of two witnesses.

ARTHUR TREVOR DAWSON. JAMES HORNE. Witnesses to the signature of Arthur Trevor Dawson:

HENRY KING, JNO. R. CASWELL. Witnesses to the signature of James Horne:

W. H. ATKINSON, I. W. MURRAY.

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