US1072648A

US1072648A - Automatic turret-lathe.

Info

Publication number: US1072648A
Application number: US41199408A
Authority: US
Inventors: James Charles Potter
Original assignee: POTTER AND JOHNSTON MACHINE CO
Current assignee: POTTER AND JOHNSTON MACHINE CO
Priority date: 1908-01-21
Filing date: 1908-01-21
Publication date: 1913-09-09
Anticipated expiration: 1930-09-09

Description

. J. o. POTTER.

AUTOMATIC TUBRBT LATHB.

APPLIOATIDN FILED JAN.21, 1908.

'Lupus-SHEET z.

Patented Sept vwentoz Wi h1 zoom J. e. QPOTTER.- AUTOMATIC TURBET LATAHE. APPLIoATIoN FILED JAN. 21, 19oa.

Patented Sept. 9, 1913.

'1 SHEETS-amm s.

Snom/fiez `Mw @am J. G. POTTER.

AUTOMATIC TURRET LATHB.

APPLICATION FILED IAN. 21, 190s.

1,072,648. Patented sept.9,1913.

v 7 SHEETS-SHEET 4.

@vi h4 mozo J. G. POTTER.

AUTOMATIC TURRBT LATHB.

APPLIGATLON FILED JAN.21, 190B.

1,072,648, Patented sepc.9,1913.

7 SHEETS-SHEET 5.

` HAM/ea am] J. C. POTTER. AUTOMATIC TURRET LATHB.

APPLIOATION FILED JAN. 21, 1908.

. 1,072,648 v Patented' sept. 9, 1913.

` '7 SHEETS-SHEET e.

J. C. POTTER. AUTOMATIC TRRT LATHE. A PPLIUATION FILED uuml, 1908.

1,072,648. y Patented sep1;.9,1913.

7 SHEETS-SHEET 7.

l EMM/yy RHODE ISLANn.

STAT-Es PATENT cierren.

" JAMES-@Hmm PQFTEE. QF PAWTUGKET. 33993@ ISLANP, SIGrNQB T0 FOTTR AND JOHNSTON lltiGIIIlWIl (20 OFQEAWTUCKET. 3130.121? ISLAND, CORPORATION 0F ,AUTOMATIQ TURRET-LATHE.

Patenten sept. a, 1913,

Application filed January 21, 199B. Serial No. 411,994.

, To all whom t may" concern,"

` and'- lexact description thereof, re

'-.Be it known thatI, JAMES C. Porras, ra citizen of theriitedy States,- and resident of Pawtucket, in the county of Providence, and inthe `State of Rhode Island, have invented a certain new andusef'ul Improvement in `Automatic Turret-Lathes, and do hereby declare that thefollowing isl a full, clear, erence hef ing had to the accompanying drawings, in Which-.-

Figure l is a top plan view'of a turret lathe embodying myinvention, the turret vand chuckheing omitted. Fig. 2 a trout elevation, partly in section, of the same;

Fig. '3 a cross section on the line y25x-3 of Fig. 2; Fig. 4 a detail view, partly in plan `and partly in section, showing the slide reciprocating bar with the parts inthe osition `they voccupy at the beginning of) the forward movement of the slide; Fig. 5 af detail view in plan of a portion ofthe under side of the bar with the cam grooves;

Fig. 6 a section on the line 6 6 of Fig. 5; Fig.' 7 a rear elevation showing the gearing at the head stock end; Fig. 8 an end elevation of a portion of the machine looking toward the head stock; Figs. 9 and 10 are de-j tail views of the devices operated by the star wheel vfor changing the gear connections; vand Fig. 1l a section on the line 11-11 i the spindle.

My invention' relates to feed mechanism fonlathes, and the type of lathe in which `I "have embodied my inv ntion, is-the fa#` of Fig. 1, showing the clutch miliar turretllathe in w ich a cam drum is employed to. reciprocatethe turret slide, and' tho particular object I have had in view in makingf'my nventiom'isto improve the machine which v.forms the subject of my United-States Patent, No. 880,916, dated Marclif5-r'l908, in which machinethere is provided fa lslide moving mechanism in add` tion to` the cam drum, by means of which the length of feed or travel of the turret slidemay be as great as desired,'independ connection of vthis problem by thev previsione-f slide-re- -heretofore, because the mechanism by which the turret slide is moved when the cam is not acting thereQD, can be made to move the turret slide at a muchy higher speed than it canbemoved by the cam,and I time the 6 vmovement: of the cam drum so that the proper cam is 1n readiness to begin its work the instant that the other slide moving mechanism finishes its portion of the movement of the turret slide.

Referrin now to the drawings, A designates the rame of a turret lathe; B the head stock, in which is'journaled the spindie C, carrying t-he chuck e; D the slide on which is mounted the tool turret E; and F vthe cam-carrying drum, all which part-s are, or-may b e, of usual construction, and therefore need no particular description.

vAttached to the bottom of the turret slide D, lengthwise thereof, is a bar G, the attaching means consisting of bolts H and a l1-slot. so that, when desired, the lslide may be shifted relative Vto the bar to change its position. On the inner-or forward end of the bar G and on the bottom thereof, is a cam-engaging projection in the formof an anti-friction roller g which by the action of the cams f on the drum F moves the turret toward and from the headv stock in the usual manner. As I have explained in my former patent, the extent of travel of the turret slide by the cams f is a limited one and any increase in 'its travel by the use ofthe cams is objectionable because of its compelling an increase in the height of the machine, and 'yet the demands of the work on t-hese machines requires an increase of l the travell ofthe turret slide. I have solved ciprocating means additional or supplementary to the cams, and in the embodiment of my invention shown in the. accompanying drawings, such means consist of Arack teeth g on. one side of the bar G, a v

pinion I in mesh therewith, and mounted 100 'on -the upperzend of a'short .vert-ical'shaft K, a bevel gear 1L on the lower'endof said shaft. K, two bevel pinion M meshingwith. the bevel gear on diametrically opposite c sides.v thereof and loosely mounted on a 105 v.short horizontal shaft N, with which they are adapted to be'. alternately clutched, so that the pinion I may be revolved in either direction, and agear wheel 4o .on vthe shaft N,Iwhclihy gears o2 receives motion from a 1 the head stock, all as more fully described hereinafter.

Each of the bevel pinions M has a :clutch Q face, and between them a lclutch collar S is v longitudina splined to the shaft N andis movable so that it may clutch either or neither pinion thereto. Said fcollar S is lengaged by a lever T on the lower end 'fof a vertical shaft, which at its upper end has an arm V having a'roller a situated in a cam path or`slot inthe'slide-actuatingbar'G, said slot or cam being icom osed of a centrally disposed lily extending straight path` W, and two longitudinally'extending straight paths W .and W2 arranged o'n either side of the transverse center of the bar, and connected with said centrally disposed path W by paths that diverge therefrom, and in one of said paths, as is common with this type of cam, there is a switch latch or gate w which permits the arm roller .o topass from the centrally disposed path W into f only one (the path W) of the other straight paths. Said other, parallel, straight paths'are connected at their ends o posite the single, central path, and when t e roller has traversed the ath W it is moved to, the other W2 and the clutch collar-S thereby shifted) by means of a coil spring` X mountedi-n an extension ofthe roller-carrying arm V'with one end bearing thereagainst and the other end, through the medium of a closed-ended tube or casing n3, bearing against a surface on the machine fiame A. When the arm roller 'v is in the centrally disposed path'W,

the clutch collar S is held in midposition so that 'neither bevel pinion'M is in mesh with the bevel gear L, and thus no motion I be transmitted to the bar G thereby. 4

It will be seen that by the reciprocation of the bar G, with its cam` paths, the clutch'collar S, so long as the arm roller v is in the centrally di osed pathpW, will be maintained in mi -position, and no'm'ovement be imparted to the turret slideby the piston I and rack, or said collar will be shlftedto clutch one or the other of the bevel pinions Mio their shaft so as to revolve the rack-engaging pinion I and lmove the turret' slide toward or from the work, according to which of the bevel pinions M i's' clutched to its shaft, such rotation of the bevel pinion, and consequent travel of the 'turret slide, continuing so long as the arm roller D is in the respective cam pa'th W' or W2. vDuring the time the arm roller lv is in the centrally disposed path W and of the consequent inaction' of the rack-enga 'ng pinion I, the turret slide is moved by t e action of a cam f on the pe-` riphery of the cam drum F, andthe move ment ofthe turret slide' at this time in one path direction is for lfeeding the tool while doing its work, while during the time the arm roller 'v is in one of the strai ht none of the4 cams fof tie rum F acts on'the projection or roller g of the bar G, and the travel of the turretslide is produced wholly by the rotation of the pinion I, and the extent of the travel of such slide is, of course, entirely dependent upon the length ofthe rack and of the straight paths lW or W2, which length maybe any that is de sired. The movement of the bar G and the turret slide during the time the clutch collar ,S islbeing shifted from one of its positions Vin the end of the'straight path W2 nearest the work, and that bevel pinion M which rotates the `pinion I in the direction to4 move the turret slide toward the Work will be clutched, to its shaft and will remain so clutched until the arm roller f'v has traversed the length of the path W2 and reaches the 2 switch latch or gate, at` which time one of the feed cams f on the drum F will en age the projection -or roller g on the bar that further forward movement of the G and the turret slide, and the clutch collar F, to mid-positionby the,

bar

passageof the Iarm .fv to the inner end of the" v straight path W will be effected by 'the' ac-'V tion of said cam f. vThis forward travel of the turret slide while the arm roller/v vis in the straight path W2 is utilized to bring'theturrettool which -i's to be used into osltion the shiftingiofl tobegin its work, and if, for examp e, such tool is a boring bar Y, it enables the portion of the latter in advance of the cutters to pass through the work supported by-the chuck and enter a pilot bushing in the end of the spindle, so that, so to speak, the turret and spindle 4will be tied together -and the boring bar rigidly supported atboth ends IWhile the cutting vor boringv is being done. It will,

work is a long piece, whether the amount of work to be doney is long or short, I am enabled to rigidly support the tool-carrying bar at both ends. I have referred to the use of -a boring bar merely as an illustration, for, aSwill be seen from the illustration in Fi 2 of the drawings, a tool Z for doing outsi e work maybe used, such tool ZI being mounted upon a bar that at one end is secured to the turret. During the travel of the turret slide when the arm roller v is in the straight path W the turret slide is moved to withtherefore, be evident that if the subject of arm' roller 'v is in the straight path v.Vz by the action of the rack and pinion, the extreme portion of the rearward travel of the turret slide being effected by one of the return cams f on the cam drum F. A The gearing for revolving theshaft P' is such that the turret kslide is 'moved atas high a speed as is desired, rearward fromthe work, until withina short distance of the end of its rearward travel, when its speed is reduced to give time for the automatic revolution 'of the turret, without danger of damaging the turret locking stud and to avoid damage, from the momentum of the parts at a high speed, in arresting the rearward travel of :the turret slide and reversin such travel, and for the greaterportion o its forward travel, after its reversal, the turret slide is moved at as high a rate of speed as desired. I Will now describe the gearing by which I secure such movement of the turret slide.- Journaled loosely on the shaft P, is a gear A' which is geared to the lathe spindle, which is revolved from a band wheel B', keyed to a shaft B2 journaled in bearings on the head stock,`to which band Wheel a belt runs from a counter shaft. A`

train of gears Bs transmits motion from the pulley shaft B2 to a shaft B4 having a' gear B5 which meshes with the gear A', and from the shaft B4 by change gears B power is transmitted to a shaft B" having a pinion -B8 which meshes with a gear B9 on the spindle C, and which drives the spindle C through the clutch connection illustrated in' Fig. 11, .and which is similar to that shown in United States patent issued to Potter & Johnston Machine Co., No. 761,905, June 17, 1904. Connected to the gear .A' by means of asleeve C', is a pinion D' that is in mesh with a gear E'on a shaft F' journaled in bearings on the head stock of the lathe. The gear E is loose on the shaft F', and has on one side a hub or collar G', which forms one member of a clutch, the other member of the clutch being a collar I' which is keyed to the shaft and has clutch teeth 'or pins z" adapted to engage the'hub G' by the sliding `of the gear and its hub, so that when said clutch members are engaged, the shaft F will be revolved by means of the pinion'D' and its intermeshing gear E'. On the shaft F', is a comparatively large gear K', which meshes with a pinion L' on the shaft P. so that when the gear E' is clutched to the shaft F', the shaft P will be revolved by means of the gear K' and the pinion L', and at such arate of revolution as to impart a high speed to the turret slide. The gear E' also has clutch teeth or pins e adapted to enga-ge a clutch hub or sleeve M', journaled loosely on the shaft F', and

movements in opposite directions.

connected to a gear N', which is in mesh with a gear O', of like diameter keyed to the shaft P. The gear N', when its clutch hub or sleeve is interlocked with the gear E', will be revolved by the gear E', and as at thistime the gear E' isunclutched from the shaft F', the revolution of the shaft P ywill vbe derived from the lintermeshing of the gearsv N and O', and such revolution will be at the rate to impart the slow movement to the turret slide, which is desired, to give time for the automatic revolution of the turret and the reversalof the travel of the l turret slide.

The operation of the clutches by which the gear connections are changed, is effected automatically. For sliding the gear E', the

mechanism employed is as follows: Engaging an annular groove inthe gear hub or collar G', is one arm of a lever p', pivoted to a bracket on the frame A of the machine, and connected to the other arm of said lever p'. is a yoke-shaped sleeveP' that is slidably mounted on a shaft Q' placed in bear-l ings on the frame A, so as to lie parallel with the lathe spindle.- Fixed to the shaft Q', at one side of the sleeve, is a sleeve or collar R', which on its end next the yokeshaped sleeve P', has several inclined or cam surfaces adapted to co-act with similar surfacesl on the adjacent end of the yokeshaped sleeve, and by the revolution of the shaft Q. the cam surfaces acting upon each other will move the yoke-shaped sleeve longitudinally, and thereby move the lever 20' in one direction. The yoke-shaped sleeve is moved in the opposite direction to rock the clutch lever p in the reverse direction, by means of a coil spring S. The shaftvQ is rotated intermittently, or step by step, so

that the to and fro movement of the yokeshaped sleeve willy take place in succession and with an interval of time between its To so rotate the shaft Q', ithas upon one end a. star' wheel T', whose teeth are-a'ds'tpted- `to be engaged in succession,..by" pins or studs u', secured to the side of a wheel U', fixed to the cam drum shaft V' The movements of the yoke-shaped sleeve P' are transmitted to the clutch lever p', by means of a cam path p2 formed in an arm of said sleeve P', which vengages a stud or roller on one arm of a bell crank lever p3, the other arm of said bell crank lever being pivotally connected to one end of a lever p4, whose other end is pivotally connected to an arm p5 on the shaft 7? of the clutch lever p'.

As is usual with the class of machines to which my invention relates, the cam drum is driven by power taken from a band wheel o von the lathe spindle C, the belt from the vband wheel e being run to a pulley W' of a Machine- Co., No. 761,905, June 17 1904. Belsides driving the cam drum from the lathe spindle through the diii'erential gear, the cam drum is driven at a higher rate of speed than that imparted to it through the differential gear, by a train of gearing which includes a pinion X. upon the shaft F, which pinion meshes with agear Y,'from which motion is transmitted to the cam drum. Although, as will be seen, both the lathe spindie and the shaft F are geared to the cam drum', and the gear connection between the shaft F andthe cam drum is such that a higher` speed of revolution is imparted to the cam drum, than from the lathe spindle, this is possible, because just as in the case of the machine in the above mentioned patent, and as illustrated inv Fig. 11, a-form of clutch mechanism is employed with the'lathe s indle C, which permits the lathe spindle to revolve independently of and faster than its driving mechanism revolves it, such faster revolution of the lathe spindle C taking place when the cam drum receives its motion from the shaft F.

It will be seen thatfjthe connection from the driving member, such as the pulley B on the shaft B2', to the turret slide for imparting the return movements to said slide, is independent of t-he Aconnection from said driving member to the work spindle, sc that said return movements will not be in any way affected by variations in the speed of the spindle, but`will instead remain constant and uniform so long as the speed of the driv` ing memberremains constant. It will also be seen that the feeding movements of the turret slide are in unison with or in harmony with the speed of the `work spindle, so that when, for example, different change gears are used, the speed of the s indle is changed, the feeding movements o the turret slide will be correspondingly changed. Y

The means by which motion is transmitted to the drum F from the shaft F through the pinion X and gear Y', are as best shown in .Figs 2 and 8, a pinion 11 alongside the gear Y', a gear H1 with whichl said pinion meshes o-n a shaft G10 having at one end a pinion F19 that meshes with a gear E1 on the cam drum F. As will bev seen by reference to Patent No. 761,905, hereinbefore re- 4 ferred to, the pins u of the speed changing wheel U' are adjustable, so that thcrebythe time of shifting the gear connect-ions with the shaft F may be fixed vas desired, andv thus the time when the return movement of the turret slide at the highest speed through the gears X and Y may be determined. Thus, since theshaft F is geared directly with the cam drum F,.so that the latter need not be driven through. the diii'erential gear,

the pins u of thespeed changing wheel may be adjusted so as to render the shaft FA Yactive to drive the cam drum for the return sleeve M of the gear N', is a lever Z', which normally tends to move the gear N and its clutch hub M to a position where it will' 30 vbe unclutched. from the gear E', as by means of a spring o'r weight z For moving said gear AN and :its clutch hub in the opposite direction, to engage the same with the gear E', a pitman or rod A2 is connected to and extends from said lever to a bell crank lever B2 pivoted to the machine frame, which has on one of its arms a stud or roller b2 which engages a cam -p'a'th g2 in the bar G vof the turret slide moving mechanism, which cam path has such form as to produce the shifting of the gear N and its clutch hub ,M' into engagement'with the gear EVwhen the turret slide is traveling from the work and at the time when the speed of travel of the turret slide is to be reduced, and to main# tain the engagement between the clutch hub of gear M and the gear E until therevolution of the turret, which takes place at the lower speed, is acco plished, and the turret slide h s reverse its direction of travel and hasaaveled a shortdisnce to- Yward the work, whereupon the gear N and its clutch hub M', will be moved to disengage the same from the ear E', at which time also the gear Ev w1l1 be clutched `to the shaft F', through the star wheel mechanism I have already described, to place the high speed gearing for the turret slide into operation, as well'as the high speed gearing 110 for vrevolving the cam drum.

The operation of the machine illustrated and described, is as follows: The travel of the turret slide while work is being done, is produced by engagement of the proper cam 115 plate`of the cam drum with the` stud or .roller g of the turret slide, the revolution of the cam drum at such time being caused by the belt connection between the lathe spindle and the differentialV gear, -and the return' 180 -movement of the turret slide, after the completion of the work of the tool, is likewise produced by vthe appropriate cam plate of the cam drum until a point is reached in the, rearward travel of the turret Slide, when b. 1&5 the action of the cam 'path in the 4bar upon the clutch operating lever T, the turret' slide is coupled tothe shaft P, whereupon Vthe further rearward movement of the turret slide is at the highv rate of' speed im- 130 The f parted by the shaft I), due to the coupling of said shaft to the shaft F through the pinion L and gear K.

bar G, the clutch collar G onthe shaft F is moved by the star Wheel. actuated devices to clutch the 'gear E to the shaft F so that the latter may be drivenjbyfthe vgeargcon nections hereinbefore." described, from'fth'e head stock shaft having, the band Wheel B."

Since the shaftI",isnow'being drivenjor-revol ved as.. described, the-'pinion X'fon'the .shaft F throughthe ear Y', imparts-motion tothe ca-m drum siaftthrough the difij'sgiriven by-its belt conlatlie spindle,V so that the "mfdrum isincreased to ofthe turret-suda point rearwardtr A 'fr the turret slide,=to enable the automat-ic jrevolution of thev turret atsuch a rate of speedas'not to lresult-in damage. to thejlccking lstud or other parts,

and also to avcid'jthe shock which' would result'from the arresting and reversing ofthe travel of the 'turret slide with its heavy parts at a high speed. To efect'this slowing downof the motion of the turret slide, the clutch collar G is.l shifted to disconnect the gear E from the shaft F', which operav t-ion is produced by the action of the star wheel actuated mechanism, and by the shifting of the clutch hub M of the gear N, into engagement with the clutch pins or studs on the gear E', which movementof the clutch hub M is produced by the cam path g2 in the har (t, which operates the bell crank lever B2, thus gearing the shaft I to the gear N', which meshing with the gear O- on the shaft I), revolves the latter at the lower speed desired. Asthe gear E is at this time .unclutched from the shaft. F, the latter ceases to be the means -for revolving the caindrum, which is again driven by its belt connection with the lathe spindle. The rearward travel of the turret slide at the slow speed, being completed, and its travel reversed, the clutch hub is `shift-cd in the direction to disengagevit and the gear wheel E', by 'the operation of the cam path g2 in the har G, and at' the Sametime the clutch hub of the gear E is moved by the action of the star wheel actuated devices to again clutch the gear wheel E vto the shaft It", to couple the turret slide and the cam drum aga-in to the high speed gearing, to move the turret slide forward to the point where the At the same timel that the shaft P is coupled to the'turret slide- 'lle ncrc'ased rate of travely e n n orderthata cam .plate flef-the cam drum fiay vesirel to slow down the work of the tool is to be in, whichpoint be-` ing reached, the turret s ide stud or 'roller g will beimmediately engaged by the 'proper feeding cam" plate on the cam drum, whereuponthe further onward travel of the turret slide will be etfect'ed by said cam drum.

It willbe seen that as the shiftin of the clutch hub AM to render the gear orinactive upon the shaft P, is accomplished by mechanism that is o erated from the turretslide, the change o speed of the turret in the travel of the turret slide.

illustrated and described in detai the construction -of a particular machine, in which I have embodied my invention, the scope of my invention is Anot limited or restricted to the machine-of such or any particular construction.

Havin what I c aim is :Y t v 1. In a feed mechanism for feeding a tool, thepcombination of a' traversable tool holder, a drum having cams arranged to act in succession to move the tool holder during one part of its traverse for the performance of work by' the tool, separate` means arranged to be effective upon said. tool holder to move it during another part of its traverse, at a different speed, ear

thus .described my invention,

active Vslide'is certain to occur at the properpvtime ing for revolving the drum at wor ing A speed, other gearing for revolving the drum.

at a diii'erent speed, and mea-ns to drive thel drum through oneV other. l .p

2. In a feed meclmnisx-n 'ffor feedinga of said gearing or the tool, the combination of a traversable"toolv holder, mechanism for` `moving the tool holder during one part of its traverse for the performance of work by the tool, separate mechanism arranged to be ,effective` upon said tool holder to move it during anotherpart of its traverse, and'means te vary the speed at which the tool holder is moved by said separate mechanism to cause it to move at ditferent speeds during differ ent portions of its travel.

In a feed mechanism vfor feeding a tool, the combination of a turret-'r slide, a cam drum for moving the slide while *work is being done, a separate mechanism for im parting movement` of the slide at other ti-mes, and automatic means for slowing' 'downthe movement j of the slide by said separate mechanism at the end of its travel from the work.-

4. In a feed mechanism for feeding a toolfthe combination of a traversable tool holder, a cam drum to move the tool 'holder during one part of its travel, separate means to move said' tool holder during another part of its travel, gearing for revolving the drum` forl the performance of Work, 'other gearing for revolving the drum at a higher rate of. speed,`\automatic means to change the gear connections for revolving the drum so that said higher rate of speed is im parted to thedrum when the tool holder is moved by said separate means.

5. In a feed mechanism for feeding a tool, the combination of a traversable tool holder, a cam drum to move the tool holdel during one part of its travel, separate means to move said tool holder during an other part of its travel, gearing for revolving the drum for performing work, other gearing for revolving the drum at a higher rate of speed, connected with said separate tool holder moving means, and means for changing the connection between said other gearing and the drum so that the drum will revolve at the higher speed when said separate means is actmg on the tool holder.

6. In a feed mechanism for turret lathes the-combination of a turret slide, two slide moving .means effective upon the slide t( move it during different parts of its travel one of which means moves -the slide when Work is not being done, means for varying the-speed of the slide during its travel wher work is not be' done, and mechanism operated by the slide for controlling said speed-changing means.

7. The combination of the lathe spindle,

the turret slide, a-cam drum, a driving member, a train of gearing connecting the spindlev and the cam drum, a se arate train of gearing connecting the spin le and the turret slide, other gearing between the driving member and the cam drum, and means to change the gear connections between the driving member and the cam drum, whereby the cam drum maybe revolved for the performance of work, and, revolved at a higher speed when work is not being per- 'time it is geared to drive it for the performance of work, and so that at another time it is geared to drive it at a higher speed when work is lnot being performed.

In testimony that I claim the foregoing I have hereunto set my hand.

JAMES CHARLES POTTER.

Witnesses:

` EARL H. Ronars,

'.CHAS. H. W. Rorm'rs.V