US1764515A - Direct-reading gear-shift mechanism - Google Patents

Description

June 17, 1930. c, M Y R 1,764,515

DIRECT READING GEAR SHIFT MECHANISM Filed June 2, 1925 4 Sheets-Sheet l Emoemtoz & :4 Ne w W UHMMM M June 17, 1930.

D. C: KLAUSMEYER DIRECT READING GEAR SHIFT MECHANISM Filed June 2, 192%; 4 Sheets-Sheet 2 June 17, 1930.

D. c. KLAUSMEYER DIRECT READING GEAR SHIFT MECHANISM Filed June 2, 1925 4 Sheets-Sheet '3 D. C. KLAUSMEYER DIRECT READING GEAR SHIFT MECHANISM Jam 17, 1930,

4 Sheets-Sheet 4 Filed June 2, 1925 avwwntor fi wM c. M flum WFMQILM Patented 'June-17, 1 930 3 "UNITED STATES;

PATENT OFF-ICE Y Devi-p c. KLAUSMEYER, or CINCINNATI, 0310, ASSIGNOR TO THE omomm'rr 31cm FORD 'roor. COMPANY, or cmcmrmrx, onro, A conronnrxon or omo DIRECT-READING GEAR-SHIFT MECHANISM Application filed June 2,

This invention relates to speed-change mechanisms for machine-tools and it deals more particularly with meansfor shifting certain-shiftable' gear-units forming a part of the speed change mechanism and to means for indicating'the result obtained by the various movements of the gear shifting levers.

In certain classes of machine tools, such for example as drilling and boring machines, a tool spindle is adapted to carry various types and sizes of tools and, as each of these toolsrequire a different speed of rotation for maximum efliciency, it is'essential that means be provided for regulating the speed of rotation of the spindle. For instance, a inch drill will operate efliciently, at a speed of 788 rotations per minute while, in the same .material, the most efficient speed of rotation for afour inch drill isin 'the neighborhood of 76 rotations per minute. Thus it will be seen that the larger the drill the slower is its efficient speed of rotation and by varying the speed of rotation inversely in proportion to the size of the drill a substantially constant peripheral speed of the tool will be maintained. A peripheral speed-of about eighty feet per minute is preferable for drills less than four inchesin diameter but it has been found that in boring a substantially slower periph eral speed is more eflicient and therefore a peripheral speed of about forty feet per minute is usually used for boring holes from 2 ,4 inches to ten inches in diameter.

To provide the necessary speed changes for the tool spindle, drilling and boring machines are usually provided with a plurality of speed change devices each com- .prising shiftable and non-shiftable gearunits, and in the most modern machine-, tools these devices are located entirely within the drill-head and the shiftable gear units thereof are adapted 'to'be shifted-by suitable levers (frequently four) located at Va rious places on the drill-head. While this location of 'all of the gear shifting levers has greatly facilitated the shifting of the gears to produce the desired spindle speed, nevertheless, the number of levers and their 1925. Serial No. 34,337.

This invention therefore has for an object to provide, in a tool-head, a plurality of speed-change devices and-so to co-ordinate the actuating levers therefor that the gears, readily and without confusion, may be shifted to give to the spindle any one of the plurality of available speeds.

Another object of this invention is so to construct the gear-shifting mechanism that the actuating levers therefor may all be grouped together in a position in which they are within easy reach of the operator when stationed at his work.

A still further. object of the invention is to provide a specially designed index plate adapted to show the preferred speed of rotation for drills and boring tools of various diameters and to cause-this index-plate to cooperate with indicators movable by certain ones of the gear-shifting levers to indicate the positions to which said certain levers must be moved and the direction in which others of the levers must be moved to produce a predetermined speed of rotation in the spindle.

These objects have been attained by combining in a drill-head primary, secondary and tertiary speed-change devices adapted to transmit to the tool-spindle any one of thirty-six speeds from a single speed in an arm shaft or other prime mover. The three speed-change devices preferably comprise a plurality of non-shiftable gear-units and four shiftable gear-units each providing gears adapted selectivelyLto be meshed with the gears of the non-shiftable gear-units. The primary and secondary speed-change devices each includes one shiftable gearunit and aflordsthree speed changes while the tertiar speed-change device (or backgears as t ey are usually called) includes "two shiftable gear-units and affords four speed changes which multiply-into thirtysix, the nine speeds provided by the primary and secondary devices. Each of the shiftable gear-units is actuated by a separate lever and,'by means of this invention, these levers are nested together in a readily accessible place on the drill-head instead of being scattered over'the drill-head as has heretofore been the practice.

The actuating levers for the primary and secondary speed change devices each control an indicator adapted to cooperate with a specially designed and suitably marked index plate carried by the drill-head, adjacent the levers, to show to the operator the required positions of adjustment of said levers to effect the proper gear setting in the primary and secondary devices to produce a predetermined speed of rotation in the tool spindle. The index plate also carries indicia which informs the operator of the direction in which the back-gear levers must be shifted to cause the tertiary device so to cooperate with the primary and secondary devices asto produce the desired spindle rotation.

Other objects and advantages will be in part indicated in the following description and in part rendered apparent therefrom in connection with the annexed drawings.

To enable others skilled in the art so fully to apprehend the underlying features hereof that they may embody the same in the various ways contemplated by this invention, drawings depicting a preferred typical construction have been annexed as a part of this disclosure and, in such drawings, like characters of reference denote corresponding parts throughout all the'views, of which Fig. 1 is a side elevation of a portion of a radial drill arm and a drill-head, embodying the present invention, carried by said arm. Fig. 2 is a sectional development of the spindle rotating mechanism embodied in the drill-head shown in Fig. 1, together with the means for shifting the shiftable gear-units comprising a part of said spindle rotating means. Fig. 3 is an enlarged detail view of the gear shifting mechanism and the index 1 plate coo erating therewith lookin in a div rection o the arrow T in Fig. 2.

ig. i is a detail plan of the back-gear shifting mechanism. Fig. 5 is a detail plan of the mechanism for shifting the gears of the primary and secondary-s eed change devices. Fig. 6 islan enlarged ace view of the speed index late.- Fig. 7 is a diagrammatic view showlng the flow of motion from the power shaft through the three "speed change devices to the spindle to be. rotated.

present multi 1e Referring to Fig. 7, the scheme of: the speed s indie-rotating mechanism wil be understoo Power isintroduced into the tool head by means of a ower shaft P (which in practice referably -15 the horizontal shaft ournaled engthwise of the radial arm) This shaft is connected, as by means of bevelled gears,-indicated at hereinbe X, to a driven shaft 1. Primary speed ond speed change mechanism B comprising gears c, h,z', j, is, Z and clutch elements 9'' and Z, triple the three speeds transmitted thereto and produce nine speeds in a shaft 3. A third speed change mechanism C connects the shaft 3 with a spindle rotating sleeve 5 and multiplies by four the nine speeds of the shaft 3 into thirty-six speeds in the sleeve 5 and to spindle S driven thereby. The four trains of mechanism for multiplying the nine speeds delivered to the mechanism C comprise :-1st, gears m, a, 0, p, shaft 4, gearsg, r and clutch elements 8 and t,'--2nd, gears m, n, and 0 and clutch element o,'--3rd, clutch elements 10, w, gears p, 0 and clutch element o,'-4th, clutch elements w, 00, shaft l, gears g, r, and clutch elements .9 and t. Thus it will be seen that by means of, three independent serially arranged speed mechanisms A, B and C, all of which. are carried by the tool head, the single speed in the shafts P and 1 is multipled into thirty-six speeds in the spindle S.

Referring now more particularly to Fig. 2 the mechanism for selectively securing any one of thirty-six speeds will be more thoroughly understood. The power shaft P ear; ries two bevel' gears (of which only one ((3) is shown) which mesh with diametrically opposite sides of a similar gear 7 fixed upon a vertical shaft 1 journaled in bearings 8 and 9 supported by the tool head. A suitable clutch mechanism (not shown) is adapted selectively to render either of the bevel gears effective to rotate the gear 7 in reverse directions. Splined to the shaft 1 is a gear-unit 10 adapted to be shifted axially on the shaft 1 by suitable mechanism later to be described. This gear-unit provides the gears a and b adaptedselectively to be meshed with gears 0 and d keyed to a shaft 2, also journaled in a tool head as by means of bearings 11 and 12. A gear-unit 13 is rotatably 1ournaled on a bushing 14 co-axial with the shaft 1 and provides a clutch element 6, ada ted to be engaged by'a gear b, and a ear permanently in mesh with gear 9 fixe upon the shaft 2. The gears a, b, 0, d, f and g and the clutch element a constitute the rimary speed-change mechanism A fore referred to (see Fi 7) which delivers three speeds to the shaft 2 from a sin 1e speed in theshaft 1.

he second speed change mechanism B, which triples the speeds in the shaft 2,.com-

head. The gears 11 and j constitute a gear unit. 17 splined to the shaft 3 and adapted tofbe shifted thereon by suit-able mechanism later to'be described. The gear Z is'rotata- .bly 'ournaled on a bushing'18, coaxial with sha t 3, and is formed with a clutch element Z adapted, in certain positions of the gearunit17, to engage a mating clutch element j on said gear-unit, thereby to establish a' driving connection between the gear Z, and" the shaf-t 3. V

The nine speeds in the shaft 3 are multis plied by four by the third speed change mechanism C, usually known as the backgears, now to be described. Upon the shaft 3 is splined a. shiftable gear-unit 19 formed with a gear m and a clutch element to. The clutch element is adapted .to'be brought into driving engagement with a clutch element m/formed on a member 20 fixed'upon a shaft '4 journaled in the: tool head with its axis position of the member, to engage the gear 0- in line with the axis of the shaft3. The shaft 4-carries a gear 9 which is adapted to transmit slow rotary motion to the sleeve 5 andspindle S through its connection with the large gear 1', provided by a gear member 21, rotatably journaled co-axial with said sleeve and adapted to be secured thereto by 'meansof the clutch element .9, This clutch I tool head27. Nuts 28 threaded on opposite ends of the sleeve en age the bearings and 26 andprevent "en w1se movement of the sleeve in the tool head. Slow motion may also be transmitted from the gear-unit 19 by meshing the gear m thereof with the gear'n forming a part of a gear-unit 23 I rotatably journaled on a bushing 24 surrounding the spindle. The gear-unit 23-also provides a gear 0 which is permanently in mesh with the gear p provided by the member 20. With the gears m and n in mesh power flows from the gear-unit 19-through the gears o and p to the member 20 and thence through shaft 4, gears q and 1' and clutches s and t, to thespindle driving sleeve 5. The clutch member 22 also provides a clutch element '0 adapted, in the lowermost and then receiye motion from the gear-unit -19, in through clutch member to and m and gears ip and 0 or gears m, n and 0.

The gear-unit 10 of the speed change de.-'

vice A, is adapted to be shifted'le'ngthwise of the shaft 1 by means'of a lever 30 ful- .crumedbna stud 31 and is provided with. a

gear-segment 32 adapted to mesh with a rack 33 provided by a bar 34 slidablymounted in the tool-head. Adjacent its upper end the bar 34 is provided with a rack 35 maintained vpermanently in mesh with the teeth 7 of a gear-segment 36 fixed upon one end of a horizontally disposed shaft '37 journaled in l the tool head. To the opposite end of the shaft 37 is secured an arm 38 carrying at its free end a shoe 39 adapted to track an annular groove 40 in the gear-unit 10. Thus it will be seen that movement of the lever about the axis of the stud 31 will, through the connections described, cause vertical movement of the gear-unit 10, selectively to engage the gears a, c, bd or the gear I) and the clutch element 6.

The arm 38 is provided with a segmental portion 41 formed with " detent notches 42, 43 and 44, adapted to receive a spring detent '45,carried by the tool-head, .to prevent acci- 54 which tracks an annular groove 55 3 in 'the gear-unit 17. Thus it will be seen that movement of the lever 46 about the stud 31 will, through the connections described,

shift the gear-unit 17 axially on the shaft- 3 selectively to mesh the gears h--i, cj and the clutch elements 7' and Z. v

The arm 53 is also formed with a segmental extension 56 provided with detent notches 56 56", and 56 adapted to receive a spring detent 57 to prevent accidental movement of the gear-unit 17 The speed-change device C (or the back gears as they are frequently called) includes two shiftable gear units, 19 and 22. Of these, the former is provided with an annular grove 58 within which is fitted a shoe 59 carried by. a gear-shifting arm 60 fixed to a short shaft 61 journaledin the drill-head. This shaft also carries an, arm

62 having a pivotal connection with the upper end of a bar 63 mounted for vertical movement in the drill head. The lower end of the bar 63 is formed as a rackwhich meshes with a gear-segment 64 forming a part of a gear shifting lever .65 'ournaledj' upon a shaft 66 carried by the rill-head adjacent the stud 31. A spring detent 67 engages detent'notches in the r ee end of' the arm 60 to prevent accidental shifting of the ear-unit 19.

e gear-unit 22 likewise is ada ted to be shifted by means of a lever 68, ulcrumed about the shaft 66 and formed with a gearsegment 69 which meshes with a rack70 on Y rotatabl journaled in the drill-head above the sha t 61. The other end of the shaft 73 has secured to it an arm 74 which carries a shoe 75 fitted to an annular groove 76 in the gear unit 22. A spring detent 77 engages detent notches in the arm 74 and acts to prevent accidental shifting of the gear-unit 22.

From the foregoing, it will be perceived that each of the shiftable gear-units of the speed change devices A, B and C is adapted to be shifted by a separated lever and these levers are all grouped together in a place where they are withineasy reach of the operator when stationed at his work.

An important feature of this invention consists in the provision of means for showing to the operator the preferred speed of rotation for tools of various. types and diameters and the necessary adjustment of the gear shifting levers to produce, in the tool spindle, any one of the thirty-six available speeds.- To that end a specially designed speed index plate P is secured to the drillhead adjacent the gear shifting levers and cooperates with indicators H and I carried by the'bars 49 and 34 respectively. The index plate Pis provided with indicia arranged in transverse rows and consisting of nine horizontally disposed rows, corresponding to the'iiine speeds provided in the primary and secondary speed change devices, and four vertical rows corresponding to the four speeds provided by the back-gears. Each division of the indicia includes a tool size and a preferred speed of rotation for that tool.

The indicator H is preferably in the form of a plate having splaced portions h and it partly overlying t e plate P and having intermediate "said portions a notch 78 corresponding in width to three of the horizontal rows of indicia on the speed plate. Therefore in each of the three vertical positions of the bar 49, corresponding to the three vertical positions of the gear-unit 17,

the notch 78 will lie opposite, and thereby segregate from the entire plate, one of three groups of indicia. Each of these groups comprises three horizontal rows of indicia. These groups are designated as P P and P in Fig. 6.

The indicator I consists of a late fixed to the bar 34 forming a part of t e means for shifting the 'ear-unit 10. This indicator is formed wit three spaced pointers i i and'i so positioned that they lie adjacent the groups P P and P respectively. These pointers are so constructed and arranged that two of them are always maintained behind the porjecting portions 72 and h of the indicator H and one of them is visible through the notch 78 in each of the three vertical positions of the indicator H. As hereinbefore described the bar 34 is adapted each of the four vertical rows of indicia, with arrows indicating the direction of movement required for each of the levers 68 and 65 to mesh the gears of the tertiary speed change' device to complete. the driving connection from the shaft 1 to the spindle sleeve so as to produce the desired spindle speed.

Presupposing that it is desired to drill a 1 inch hole and the necessary drill has been secured in the spindle, the operation of the gear shifting means, in conjunction with the improved speed plate to give the spindle its most efficient speed of rotation, is as follows: The operator first shifts the lever 46 to bring the notch 78 in the indicator H into registry with the group of the indicia containing the size of the drill to be used,

which in this instance is thegroup P This movement of the lever shifts the gear-unit to its intermediate operative position, in which position the gears a and j are meshed. With the notch 78 adjacent the group P the pointer 1' of the indicator I is visible in the notch. The operator then shifts the lever 30 to the position necessary to bring the pointer 71 in registry with the single horizontal line containing the 1% inch drill size which, it will be observed, is the lowermost line in group P This movementof the lever 30 shifts the gear-unit 10 to its uppermost operative position which engages the gear a and the gear 0. Thus through manipulation of the levers 46 and 30 a drive has been established from the shaft 1 to the shaft 3 through gears a, c and Now by observing the arrows y and a above the vertical column containing the 1% inch drill size the operator is advised as to the necessary movement to be given to the back- gear levers 68 and 65 to complete the drive to the spindle at the required speed. By observing these arrows the operator finds that the lever on the left, which is the lever 68, must be swung upwardly as indicated by the arrow y, while the lever on the right (the lever 65) must be swung downwardly in accordance with the arrow .2. Upward movement of the lever 68 shifts the gearunit 22 downwardly which engages the clutch element o with the gear 0 and downward movement of the lever 65 shifts the gear-unit l9 downwardly also, thereby engaging the gears m and n. Thus by manipdescribed, that is by first shifting the lever 46 to segregate one of the group P, P or P containing the desired speed, then by shifting the lever 30 to bring one of the pointers 2', or i to the single horizontal row containing the desired speed, and then by shifting the back gear levers in accordance with the arrows above the vertical column containing the'desired speed:

Forcertain operationsuch as the drilling of holes from inch -,to 4 inches in diameter a certain peripheral speed is desirable whereas for other operations such as the boring of holes from 2% inchesto 10 inches in diameter a materially slower peripheral speed is desirable. The gear ratios are such that for the first named group a peripheral speed of about eighty feet is provided. For the last named roup, a peripheral speed of about forty eet is desirable'and the gears are therefore ratioed to produce that result. To indicate to the operator the peripheral speed obtained in each of the settings, the

. settings producing the higher peripheral speeds are recorded on a back ground of one color whereas the settings to produce a; slower peripheral speed are recorded on a back ground of a contrasting color and therefore the operator readily may select the peripheral speed most suited to the operation to be performed. For convenience, the higher peripheral speeds are illustrated in the drawing on a white back ground and the slower peripheral speeds are drawn on a back ground shaded to indicate red, but any levers therefor are all grouped together in a small area where the operator may reach them'all in a single position of his arm.

Also the invention provides indicating means which cooperates with the gear shifting mechanism to. facilitate ,the setting of the levers to produce any desired spindle speed and also to indicate the peripheral speed 'roduced.

.W will so fully reveal the gist of this invention' that others can by applying current to knowledge, readily ja apt it for various util izations by retaining one or more of the features that from the standpoint of the fiioruzrt fairly constitute essential characteristics of either the genericor specific as- 565 pects of this invention, and therefore such said gear shifting means to ,spindle anyone of the spec s depicted in out further 'analysis,;the' foregoingadaptations should be, and are intended to be, comprehended within the meaning and range of equivalency of the following claims. Having thus revealed this invention, I claim as new and desire to secure the following combinations and elements, or, equivalents thereof, by Letters Patent of the United States 1. In a machine-tool; a rotatable member;

a driveshaft; a plurality of speed-change devices adapted to rotate said member at a plurality of speeds from a single speed in said drive shaft, each of said speed-change devices including at least one shiftabl'e gearunit; independentmeans for shifting each of said gear-units; and can indexphysically cooperating with said gear-shifting means and designed by such co-operation to show to the operator the required position of ad'ustinent for certain ones of said gear shi ing means and to show graphically the required direction of movement of others ofsaid gear shifting means to produce a speed in said member.

2. In a drilling machine; a drill-head; a spindle rotatably journaled in -nsaid drillhead; a drive-shaft; a multiple speed driving connection between said drive shaft and said spindle including a plurality of shiftable gear-units; means to shift said sh iftable gear-units, said means comprising actuatin levers grouped together on said drill-beef, andoperative connections between said levers and said gear-units; antindex carried by said drill-head adjacent said gear shifting means and depicting all of the available speeds in said spindle; an indicator movable by one of said gear' shifting means and adapted in each of the operative positions of one of said gear-units todesignate a fractional part of the entire. number of speeds depicted by said index; an-indicator movable by another of said gear shifting means and adapted in each of the operative positions of another of said gear units to designate a group of speeds comprising only a fractional part of the number of speeds designated by said first named indicator; and means to show the required movement 'of others of reduce in the predetermined the group designated by said second indicator.

3. In a machine tool, ,a drive shaft; a rotatable spindle; a multiple-speed driving lltl connection between said shaftandfsaid spin- '1 dle, said driving connectioncomprising primary, secondary and tertiary speed change devices, said primary and secondary deviceseach including one shiftable gear unit; two

shiftable gear units in said tertiary device; a

independent means to shift each of said gearunits, said means each including an actuating lever and an operative connection between said lever'and one of said gear-units;

an index depicting the various speeds available in the spindle; indicators carried by the shifting means for the gear units of said primary and secondary devices, said indicators cooperating with each other and with said index to select from the entire number of speeds depicted on said index a group of speeds corresponding in number to 'the number of speeds provided in said tertiary device; and means to indicate the setting required for the shifting means for the gears of said tertiary device to produce, in the spindle, any one of the speeds of said selected group of speeds.

4. In a machine tool, a drive shaft; a rotatable member; a multiple speed driving connection between said shaft and said member including a plurality of shiftable gearunits; means toshift said gear units to effect any one of a plurality of drives to said spindle; an index depicting, by parallel rows of indicia all of the speeds available in said member from a single speed in the drive shaft; an indicator movabl'e by the shifting means for one of said gear-units to segregate a series of said rows of indicia corresponding in number to the number of speeds provided by another of said gear units; an indicator movable by the shifting means for said last named gear unit to select one of the rows of said series; and indicia provided by said index to indicate the settings of others of said gear shifting means to efiect anyone of the speeds indicated in said one selected row.

5. In a machine tool, a drive shaft; a rotatable member; a plurality of speed change devices intermediate said drive shaft and said member to rotate the latter from the former at a plurality of speeds, said speed change devices including. shiftable gearunits; means to shift said gear-units; an

index depicting, in transverse rows, thespeeds provided by said three speed change devices, the number of speeds in one row corresponding in number to the number of speeds provided by two of said speed-change devices and the number of speeds in another row corresponding to the number of speeds provided by another of said speed change devices; an indicator movable by one of said gear shifting means selectively to indicate various groups of speeds on said index; a plurality of indicators movable byanother of said gear shifting means and each adapted in the various operative positions of said last-named means to indicate one of the rows of speeds in the group selected by said first named indicator; and indicia provided by said index to indicate the required position of the other gear shifting means to produce, in said rotatable member, any one of the speeds indicated on said index.

6. In a machine tool, a speed change mechanism including a plurality'of shiftable gear-units; levers for shifting said gearunits; a speed index indicating the various speeds provided by said shiftable gears; indicators movable by two of said levers in the gear shifting movements thereof andcooperating with said index to indicate the speeds obtainable in the various positions of said two levers; and indicia to indicate the direction of movement of othersof said levers to complete the drive through said speed change mechanism to effect any one of the speeds obtainable in a predetermined setting of said first two levers.

7. In a machine tool, a drive-shaft; a rotatable member; a driving connection between said shaft and said member, said driving connection including primary, second ary and tertiary speed change devices providing respectively three, three and four speeds and each including a shiftable gear= unit; levers connected to shift said gearunits; a speed index depicting the thirty-six speeds provided by said three s eed change devices said index plate being ivided into nine parallelrows of indicia of four divisions each; an indicator actuated by one of said gear-shifting levers and adapted in each of three positions of said lever to indicate three of said rows; an indicator movable by another of said levers and ada ted in three operative positions thereof to esignate one of the said three selected rows of indicia; and arrows to indicate the direction of movement required for the levers ofthe tertiary speed change device to effect any one of the speeds in the selected row.

8. In a machine tool, a drive shaft;-a rotatable member; a multiple speed drive between said shaft and saidmember, said drive including a plurality of shiftable gears; means to shift said gears; a speed index dey picting the speeds rendered available by said multiple speed drive; a single indicator movable adjacent said index by one of said gear shifting means to indicate a certain group of said speeds; a plurality of indicators movable adjacent said index by another of said gear shifting means to indicate a certain subgroup of speeds of the group selected by said first named indicator; and means to render visible only one of said plurality of indicators at a time.

9. In a radial drill, a drill-head; a driveshaft; means embodied in said drill-head to rotate said spindle at a lurality of speeds from a single speed in said drive-shaft, said means including a plurality of serially arranged speed-change devices embodying a plurality of shiftable elements; means ineluding a plurality of levers grouped together on said drill-head for shifting said shiftable elements; indicators movable by certain ones of said levers; an operative connection between each of said levers and one of said elements; and an index showing the various spindle speeds obtainable from a single speed in said driveshaft, said index being arranged adjacent said element-shifting means and cooperating physically with the indicators movable by said levers to indicate the required positions to which certain ones of said levers must be moved, said index also indicating the required direction of movement of other of said levers to effect any available speed in said spindle.

10. In a radial drill, a drill-head; a rotatable spindle; a driveshaft; means to rotate said spindle at a substantial number of speeds from a single speed in the drive-shaft, said means including a plurality of shiftable gear-units; a shifter engaging each of said gear-units; a plurality of bars slidably mounted in said drill-head; an operative connection from each ofsaid bars to one of said gear-shifts; a plurality of levers grouped together in a substantially small area on said drill-head; operative connections between each of said levers and one of said slide-bars whereby movement of said levers shifts said gear-units; and means cooperating with said gear-shifting means, to indicate the required movements of said levers to effect a predetermined rate'of rotation in said spindle, said indicating means comprising an index plate depicting the various aw ailable rates of rotation of the spindles; means movable by certain .of said levers to isolate a relatively small group of said available rates; and indicia on said plate to indicate the required movement of other of said levers to complete the driving connection between the drive-shaft and the spindle to effect a drive at any one of the speeds in said isolated group of rates.

In witness whereof, I have hereunto subscribed my name.

DAVID C. KLAUSMEYER.

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