US2318870A - Continuous parts-heating furnace - Google Patents

Description

CONTINUOUS PART HEATING FURNACE Filed Feb. 20, 1942 4 Sheets-Sheet l INVENTOR I .RGLeYburn eau,

May 11, 1 943.

R. G. LEQITOURNIEAU 2,318,870

CONTINUOUS PART HEATiNG FURNACE Filed Feb. 20, 1942 4 Sheets-Sheet 3 INVENTOR I R. GLeY'ourne-aw May 11, R G. LE TOURNEAU 2,318,870

CONTINUOUS PART HEATING FURNACE Filed Feb. 20, ,1942 4-Sheets-Sheet 4 JAIME) INVENTOR R. 6'. Le Tourneau Patented May 11, 1943 CONTINUOUS PARTS-HEATING FURNACE Robert G. Le Tourneau, Peoria, 111., assignor to R. G. Le Tourneau, Inc., a corporation Application February 20, 1942, Serial No. 431,728

20 Claims.

This invention relates generally to a furnace for heating parts preparatory to press-forming I thereof or like operations, and in particular the invention is directed to an improved parts-heating furnace designed for continuous operation, and consequently is well suited for use in connection with mass production manufacturing; the furnace being adapted especially for heating ordnance or shell blanks, prior to press-forming the nose thereon.

The principal object of this invention is to provide a parts heating furnace which includes a driven movable platform or turntable, having a plurality of spaced parts-supporting and elevating pedestals mounted thereon, and on which pedestals the parts to be heated seat; there being a firebox mounted above said platform and having a heating chamber therein, said platforms being operative simultaneously with movement of the platform, to elevate the parts into said heating chamber at one point, and to subsequently lower the parts from the chamber at another point, and after the parts have been thoroughly heated, all being accomplished without manual attention.

A further object of the invention is to provide a parts heating furnace as above, in which each parts-supporting and elevating platform is mounted in connection with and actuated by a separate pressure fluid cylinder mounted on and J moving with the platform; the structure including unique means, in part stationary relative to the platform, to successively feed air pressure to said separate cylinders to actuate the same and elevate the pedestals, and to subsequently release or vent the air pressure from said cylinders, to effect lowering of the pedestals one after another for removal of the heated parts therefrom, and placement of other parts for heating.

An additional object of the invention is to provide a parts heating furnace which includes a driven movable platform, a firebox thereabove having a heating chamber therein, and parts supporting and elevating pedestals mounted in spaced relation on and moving with the platform, the pedestals being operative to elevate the parts into the heating chamber, to maintain the parts in said chamber for a predetermined length of time, and to then withdraw the parts from the chamber; there being mechanism provided to constantly rotate said pedestals, and consequently the supported parts, whereby the parts when disposed in said chamber are evenly heated as is desirable.

Another object is to provide a parts heating furnace which includes a driven movable platform, means forming a heating chamber thereabove, parts-supporting and elevating pedestals mounted on and moving with the platform, said pedestals each being elevated by means of a separate pressure fluid cylinder disposed therebelow, and means to supply air pressure to, or to release said pressure from, said cylinders to control elevating of the pedestals; there being instrumentalities to automatically and mechanically support the pedestals, when in raised position, independently of the air pressure control, and during the period the parts remain in the heating chamber.

It is also an object of the invention to provide a parts heating furnace, which includes a horizontal turntable having circumferentialy spaced parts-supporting and elevating pedestals mounted thereon, said pedestals being operative to automatically raise and lower at predetermined points in their circular path of travel; the furnace including a firebox disposed above the platform having a heating chamber therein, said firebox being arranged with a rotatable bottom fixed in connection and rotating with said platform, this bottom being ported in corresponding relation to and in vertical alinement with said pedestals, whereby pedestal-supported and elevated parts enter said heating chamber through said ports.

A further object of the invention is to provide a simple and inexpensive device, and yet one which will be exceedingly effective for the purpose for which it is designed.

These objects I accomplish by means of such structure and relative arrangementofrparts, as will fully appear by a perusal of the-following specification and claims. 1 i In the drawings similarcharactersof reference indicate corresponding parts in the several views: Figure l is a fragmentary sectional elevation of the parts heating furnace, the'air control means being omitted. 1 r Figure 2 is a fragmentary sectional elevation of one'of the lifting cylinders-with its piston raised, and showing the associated air control means. i Figure 3 is an enlarged fragmentary sectional elevation showing one lifting cylinder with its piston lowered, and associated air control means.- Figure 4 is a fragmentary plan View showing adjacent lifting cylinders, and air control means as associated therewith.

Figure 5 is a sectional elevation of the firebox on a reduced scale. V c

Referring now more particularly to the characters of reference on the drawings, the improved parts heating furnace comprises a substantially circular base I, to which are secured a plurality of symmetrically and circumferentially spaced vertical supporting legs 2 of substantial height. At their upper ends legs 2 support a cylindrical firebox 3, disposed with its axis in vertical alinement with the center of base I.

A circular housing 4 is mounted in suitable manner concentrically on base I, and is of substantial diameter and depth. A vertical sleevelike neck 5 is mounted centrally on and upstands from the top of housing 4; an internal shaft 6 and a surrounding tubular shaft 1 extending through neck 5, and being suitably journaled and supported for independent rotation, An electric motor 8, is mounted vertically in inverted position above housing 4, and drives the internal shaft 6, through the medium of an externally disposed endless belt 9 and pulley ID, the latter driving a shaft H, which in turn drives a train of speed reducing gears, indicated generally at l2, and one of which is fixed on the lower end' of the internal shaft 6.

The external or tubular shaft 1 is driven from shaft 6, by means of a pinion l3, fixed on shaft 6 within housing 4; such pinion driving through another gear train l4 within housing 4, and one gear of which latter gear train is fixed on the lower end of tubular shaft 1 within said housing. By virtue of the use of the above gear trains, both shafts 6 and T are rotated in the same direction at relatively slow but different speeds.

At its upper end the external tubuluar shaft 1 projects slightly beyond the upper end of neck 5, and is there secured in connection with the bottom plate of a circular turntable housing 16, which includes a top or platform plate l1.

Adjacent its periphery the turntable housing l6 supports a plurality of circumferentially spaced, vertical and mainly depending pressure fluid cylinders I8, which extend through bottom plate l5 and top plate ll of the turntable housing in journaled relation thereto; these cylinders being rotatably supported by antifriction bearings I9. Within the turntable housing each cylinder I8 is fitted with a pinion 20, these pinions meshing with a large diameter horizontally disposed master gear 2|, mounted on the upper end portion of internal shaft 6 and for rotation with it. It will thus be seen that simultaneously with rotation of the turntable housing by tubular shaft 1, the pressure fiuid cylinders will simultaneously be rotated, due to the fact that gear 2| is at the same time rotating within said turntable housing and drivingpinions 23.

Each pressure fluid cylinder includes a piston 22, from which extends a vertically and upwardly projecting piston rod 23, which terminates at its upper end above top plate I! of the turntable housing l6. Each piston rod is fitted at its upper end with a rigid horizontal pedestal disc 24, on which the parts to be heated are seated; the parts in this instance being shown as shell blanks, which must be heated for a substantial length downwardly from their upper ends, prior to press-forming the nose thereon.

The firebox 3 is of somewhat greater diameter than the turntable housing 13, and is lined about its side walls with fire brick 26, and at top and bottom with vermiculite'plaster 21. The top 28 of the firebox is dome-like, and includes a central vent 29. Burners or fuel jets 30 project into the heating chamber 3| through the top 28 of the firebox, and discharge in opposite directions at a downward angle.

The bottom 32 of the firebox is circular, and is separate and independent from the remainder of the firebox; said bottom 32 being supported in connection and for rotation with the turntable housing I6, by means of circumferentially spaced rigid supporting posts 33, which are disposed radially inwardly of the circular path of travel of the parts 25. The bottom 32 is formed with a plurality of ports 34 therethrough, said ports being of a diameter slightly greater than the diameter of the parts 25, and correspond to and are arranged in vertical alinement with the pedestal discs 24.

With energization of motor 8, the turntable platform It and firebox bottom 32 rotate together, and with actuation of pressure fiuid cylinders 18 (the means for actuating the cylinders hereinafter being described in detail), the rotating pedestal discs 24 are elevated, to project the parts 25 through ports 34 for a portion of their length, and partly into the heating chamber 3| of firebox 3, whereby the upper end portions of said parts are heated.

When the furnace is in operation, the pistons 22 in cylinders 18 are actuated, and the parts remain projected into the heating chamber for substantially one full revolution of the turntable platform. At one point in the path of travel the pressure fluid cylinders are successively controlled, so as to lower the pedestal discs for a sufficient length of time, to permit manual removal of the hot part and placement of a cold part, whereupon the cylinders actuate to raise the latter part into the heating chamber for beginning of the heating cycle. Actuation of pressure fluid cylinders 18 to control the same as above, is accomplished in the following manner:

A rigid relatively short arm 35, projects horizontally and radially from the bottom of the turntable housing adjacent each cylinder, each such arm supporting a vertically disposed valve 36, such valve depending from the arm 35 and being of the type which is normally spring closed but lever actuated to open the same; the valve includes a horizontal actuating lever 31 which projects generally parallel to the adjacent periphery of the turntable housing. At its upper end the valve 36 is connected to an outwardly opening elbow 38, the elbow at its upper and outer end being provided with one fitting of a compression coupling, this fitting indicated at 39, has a radially pointed tapering nose. At its lower end the valve 35 is connected with a length of tubing 40, which extends downward to a point adjacent the lower end of the corresponding pressure fluid cylinder l8. Each pressure fluid cylinder I8 is provided at the lower end with a plug 4|, which is fitted with a rotatable but axially immovable nipple 42; and to which nipple the tubing is connected exteriorly of the plug. As is apparent, one of the above described air feed assemblies is mounted in connection with the turntable housing, for each one of the pressure fluid cylinders I 8.

A rigid horizontal shelf 43 is fixed in connection with one of the legs 2, and projects therefrom toward the turntable F6 in a plane somewhat below the latter, as well as below arms 35. A tubular and elongated socket member 44 of a swinging arm unit, is disposed horizontally in spaced relation above shelf 43, said member being secured at one end on a pivot pin 45 supported by means of a bracket 46; socket member 44 projects from pin 45 generally in the direction of the turntable housing. The arm unit includes a plunger 48, slidably or telescopically disposed in socket member 44, and a compression spring 49 is seated in the socketmember between the bottom thereof and plunger 48, normally urging the plunger outward; movement of the plunger in the socket member being limited by a pin 50, on the plunger riding in a longitudinal slot 5| in a finger 52, secured on the socket member 44, and overhanging the plunger in parallel relation. The plunger normally projects some distance beyond the outer end ofthe socket member, and this projecting portion'of the plunger is formed with a central bore or passage 53. A nipple 54 is threaded into the plunger 48 from below, and communicates with the inner end of bore 53. A spring closed lever actuated valve 55, is secured on the lower end of nipple 54, with the valve control lever 56 upstanding alongside the finger 52, said finger carrying an adjustable stop 51, which lever 56 engages upon predetermined telescoping movement of plunger 48 into socket member 44. A flexible air supply hose 58 leads to and is connected with the other end of valve 55.

A tension spring 59 connects between an anchor 60 and the outer end of a rigid arm extension 6|, fixed on the inner end of socket member 44, and extending across and to a point beyond pivot pin 45. This tension spring normally maintains the socket member and plunger assembly in the position shown in dotted lines in Fig. 4, and against a stop S, disposed so that the plunger 48 extends at an acute angle tothe periphery of the turntable housing, and in a direction opposite to the direction of movement of said turntable, as indicated by the arrow, i. e.. off radial dead center contra to said indicated direction. At its outer end plunger 46 is provided with an axially dis posed fitting 62, in communication with bore 53, and projecting therebeyond, said fitting 62 in eluding an annular rubber seat 63, into which the taper nosed fittings 39 are adapted to successively and frictionally project, thus forming a compression coupling. The socket member and plunger assembly is disposed in such horizontal plane, that fitting 62 is in the same horizontal plane as fitting 39. As a consequence, and with rotation of the turntable housing in the direction indicated, each fitting39 will approach, engage and seat with fitting 62, thereupon swinging the arm unit, including the socket member and plunger, about pivot pin 45, and in the direction of travel of the turntable housing. As the arm unit is swung in such direction, the plunger 48 telescopes into socket member 44, to such a point that valve lever 56 engages stop 51, before the plunger reaches the end of its telescoping move ment. As a result valve 55 is opened, and air under pressure from flexible hose 58 flows through valve 55, bore 53, the engaged compression fit; tings 62 and 39, and into valve 36. Simultane' ously the lever 31 of valve 36. has engaged a cam 64 on shelf 43, and under the influence of said cam the lever has opened valve 36, permitting the air to flow through tubing 40 into the corresponding cylinder !8, forcing the piston 22 and piston rod 23 upwardly, carrying with it the pedestal disc and the part supported thereon. As the piston 22 reaches the top of its stroke, the lever 3'! of valve 36 escapes cam 64, with continued rotation of the turntable housing, closing valve 36 and holding the air pressure in the pressure fluid cylinder. At. approximately the same time the coupling fitting 62 escapes from fitting 39, and the arm unit swings back to its initial or normal position as shown in dotted lines in Fig. 4, valve 55 closing as its lever 56 backs away from stop 51.

After valve 36 closes and the turntable housing continues to rotate, the corresponding pressure fluid cylinder l8 remains under pressure for the major portion of one revolution of the turntable housing. However, in order to permit each pedestal disc and supported part to be lowered long enough to permit removal of a heated part and placement of a cold part, the pressure in each pressure fluid cylinder is vented shortly ahead of engagement of fitting 62, with the fitting 39 corresponding to the vented cylinder. This re'- lease of the air pressure from the pressure fluid cylinders is accomplished by means of a cam 65 supported from a fixed'post P, and which lever 37 of valve 36 engages in valve opening relation at the desired point. After the pressure has been released from one of the pressure fluid cylinders, and the corresponding pedestal disc has lowered, such cylinder remains inactive, and the disc lowered until the corresponding fitting 39..again en'- gages fitting 62 in coupling and pressure transmitting relation, whereupon the previously described pressure supplying operation repeats.

In some instances, particularly where relatively heavy parts are being heated, it may be necessary to provide for mechanical latching of the piston whenin fully elevated position, to avoid relying solely on air pressure for support, and thi is accomplished as follows:

A dog 66 pivoted intermediate its ends, is mounted on the top of the turntable housing adjacent each piston rod, and is normally urged into frictional engagement with the piston rod by means of a tension spring 61. The piston rod is formed with an annular groove 68, into which the dog 66 drops when the pedestal disc reaches its uppermost limit, and thereafter, until released, the dog prevents lowering of the piston rod. In order to clear the dog from the groove when the pressure is released from the pressure fluid cylinder by lever 31 engaging cam 65, the outer or free end of dog 66 rides against another cam '69, also supported from post P above cam 65. This latter cam is of sufficient extent to hold the dog free of the piston rod until the piston rod has lowered somewhat, whereupon the dog merely comes back into engagement with the piston rod, and rides the smooth or nongrooved portion thereof.

From the foregoing description it will be readily seen that I have produced such a device as substantially fulfills the objects of the invention as set forth herein.

While this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as defined by the appended claims.

Having thus described my invention what I claim as new and useful and desire to secure by Letters Patent is:

1. A continuous parts heating furnace comprising a driven platform movable through a predetermined path, a plurality of part-supporting pedestals mounted for travel with the platform and for elevation therefrom, means operative to elevate the pedestals at one point in said path, maintain the same elevated while said platform traverses a certain portion of said path, and then lower the pedestals, and means forming a heating chamber above said platform; the parts supported on said pedestals being projected into said chamber when the pedestals are elevated.

2. A structure as in claim 1, including means to rotate the pedestals whereby the supported parts revolve within the heating chamber.

3.- A continuous parts heating furnace comprising a driven platform movable through a predetermined path, a plurality of part-supporting pedestals mounted for travel with the platform and for elevation therefrom, a separate pressure fluid cylinder supporting each pedestal, pistons in said cylinder, means to control said pistons to cause the same to elevate said pedestals at one point in said path, maintain the pedestals elevated while said platform traverses a certain portion of said path, and then lower the pedestals, and means forming a heating chamber above the platform; the parts supported on the pedestals being projected into said chamber when the pedestals are elevated.

4. A continuous parts heating furnace comprising a driven platform movable through a predetermined path, a firebox mounted above said platform, said firebox forming a parts heating chamber and having a separate and movable bottom, means mounting said bottom in connection with the platform for movement therewith, a plurality of part-supporting pedestals mounted on the platform for elevation therefrom, and means operative, as the platform moves, to elevate the pedestals at one point in said path, and subsequently lower the same at another point in said path; said bottom having ports therethrough alined with said pedestals whereby supported parts project through said ports into the heating chamber when the pedestals are elevated.

5. A structure as in claim 1, in which said first named means includes a separate pressure fluid cylinder arranged in connection with each pedestal, a fluid supply conduit for and leading to each cylinder and moving with the platform,

each conduit having a normally closed valve therein, a fluid pressure supply unit mounted adjacent the platform but independently thereof, and means in part on the platform and in part on said unit operative to successively couple said unit with said conduits and simultaneously open the corresponding valve whereby to supply fluid under pressure to said cylinders, and to thereafter uncouple the unit and close the valve, and other means operative to subsequently and successively open the valves and release the fluid pressure from said cylinders.

6. A continuous parts heating furnace comprising a driven turntable, a firebox disposed above the turntable and having a parts heating chamber therein arranged to receive parts from below, a plurality of parts-supporting pedestals mounted on the turntable for elevation therefrom, and means to successively elevate and lower said pedestals at predetermined points in the annular path of travel thereof; the parts supported on said pedestals being projetced into said chamber when the pedestals are elevated.

7. A continuous parts heating furnace comprising a driven turntable, a firebox disposed above the turntable and having a parts heating chamber therein arranged to receive parts from below, a plurality of pressure fluid cylinders mounted vertically on the turntable. said cylinders including upwardly movable piston rods, a parts supporting pedestal mounted on the upper end of each rod, and means operative to control said cylinders to successively raise and lower said rods at predetermined points in the annular path of travel thereof; the parts supported on said pedestals being projected into said chamber when the rods are raised.

,8. A continuous parts heating furnace comprising a driven turntable, a firebox disposed above the turntable and having a parts heating chamber therein arranged to receive parts from below, a plurality of pressure fluid cylinders mounted vertically on the turntable. said cylinders including upwardly movable piston rods, a parts supporting pedestal mounted on the upper end of each rod, and means in part on said platform and in part separate therefrom operative to control said cylinders to successively raise and lower said rods at predetermined points in the annular path of travel thereof; the parts supported on said pedestals being projected into said chamber when the rods are raised.

9. A structure as in claim 8, in which said means includes a separate conduit leading to each cylinder, a valve in each conduit, like fittings of a compression coupling secured on and communicating with the conduits and projecting from the turntable, a single cooperating fitting being mounted independent of the turntable and arranged for successive coupling with said first named fittings, means operative when the fittings are coupled to supply fluid under pressure thereto and to simultaneously open the corresponding valve.

10. A continuous parts heating furnace comprising a driven turntable, a firebox disposed above the turntable and having a parts heating chamber therein arranegd to receive parts from below, a plurality of vertically disposed pressure fluid cylinders mounted on the turntable for bodily rotation relative thereto, means to separately rotate said cylinders, said cylinders including upwardly movable piston rods, a parts supporting pedestal mounted on the upper end of each rod, and means operative to control said cylinders to successively raise and lower said rods at predetermined points in the annular path of travel thereof; the parts supported on said pedestals being projected into said chamber when the rods are raised.

11. A structure as in claim 10, in which said cylinder rotating means comprises a pinion mounted on each cylinder, the latter being disposed in an annular arrangement, a centrally disposed master gear journaled for rotation independent of the turntable and meshing with said pinions, and drive means for said gear.

12. A continuous parts heating furnace comprising a driven turntable, means forming a heating chamber above the turntable, means on the turntable to individually support parts and successively elevate and lower the same at predetermined points whereby to move said parts into and out of said chamber, respectively, means including a plurality of pressure fluid cylinders, and mechanism to successively charge said cylinders at one of said predetermined points with fluid under pressure, and to vent said fluid pressure at another of said predetermined points; said mechanism including like coupling fittings proecting outwardly from the periphery of the turntable in corresponding relation to the cylinders, asingle cooperating fitting mounted adjacent said turntable for successive coupling engagement with said like fittings at said one point and for movement therewith through a relatively short path, and means operative when the fittings are coupled to feed fluid under pressure therethrough.

13. A structure as in claim 12, in which said single cooperating fitting is mounted on a telescopic spring extended arm unit, said unit being pivoted for swinging movement in the horizontal plane of the turntable and projecting toward the latter, a spring yieldably and normally urging the arm unit a predetermined distance from radial dead center and in a direction contra to the direction of travel of the turntable, the cooperating fittings on turntable and arm unit successively engaging with rotation of the turntable, the arm with each engagement of the fittings swinging with the turntable beyond said radial dead center, and subseuqently with separation of said fittings returning to normal position.

14. A continuous parts heating furnace comprising a driven turntable, means forming a heating chamber above the turntable, means on the turntable to individually support parts and successively elevate and lower the same at predetermined points, whereby to move said parts into and out of said chamber, respectively, said means including a plurality of pressure fluid cylinders, and mechanism to successively charge said cylinders at one of said predetermined points with fluid under pressure and to release said fluid at another of said predetermined points, said mechanism including like coupling fittings projecting outwardly from the periphery of the turntable in corresponding relation to the cylinders, a conduit connecting each fitting and the corresponding cylinder, a normally closed valve interposed In each conduit, a telepscopic normally but yieldably extended arm unit pivoted adjacent and projecting toward the turntable for swinging movement in the horizontal plane thereof, means normally but yieldably urging the arm unit in a direction contra to the direction of travel of the turntable a predetermined distance from radial dead center, a single cooperating fitting on the free end of the arm unit, said single fitting successively engaging and coupling with the like fittings with rotation of the turntable; the arm with each engagement of the fittings swinging, with the turntable beyond said radial dead center, and subsequently with separation of said fittings returning to normal position, means operative when the fittings are engaged to feed fluid under pressure therethrough, and other means to simultaneously open the corresponding valve.

15. A structure as in claim 14, in which said fluid feed means includes a normally closed pressure control valve mounted on said arm in communication with said single fitting, a flexible hose connected with said valve, and means to open said pressure control valve upon engagement of said fittings and telescoping of said arm unit.

16. A structure as in claim 14, in which said fluid feed means includes a normally closed pressure control valve mounted on said arm in communication with said single fitting, a flexible hose connected with said valve, said pressure control valve being mounted on a movable member of said arm unit including an operating lever projecting therefrom, and a stop mounted toengage said lever and open the pressure control valve upon engagement of said fittings and telescoping of said arm unit.

17. A continuous parts heating furnace comprising a driven turntable, a firebox disposed above the turntable, said firebox having a separate circular bottom, means mounting said bottom in connection with the turntable for rotation therewith, a plurality of parts supporting pedestals mounted on the platform, and means arranged to raise and lower said pedestals; said bottom of the firebox having ports 'vertically alined with said pedestals and through which ports the parts project when the pedestls are raised.

18. A continuous parts heating furnace comprising a base, a vertical tubular shaft journaled on the base, a turntable fixed on the upper end of said tubular shaft, pressure fiuid cylinders mounted vertically in annular arrangement on the turntable and for rotation relative thereto, parts supporting and elevating pedestals mounted on the cylinders, means forming a heating chamber above the turntable and into which chamber the parts project when elevated, another shaft journaled within the tubular shaft for independent rotation, a master gear on said other shaft adjacent the turntable, pinions on said cylinders meshing with said master gear, and means to rotate said tubular shaft and the other shaft at different speeds.

19. In a continuous parts heating furnace, a vertically disposed pressure fluid cylinder, a piston rod slidable in the cylinder and having a part supporting pedestal on its upper end, a heating chamber above the cylinder into which the part on the pedestal is projected when the rod is elevated, means to supply fluid pressure to the cylinder to elevate the rod, and means functioning automatically to hold the rod elevated for a predetermined period irrespective of the fluid pressure.

20. In a continuous parts heating furnace, a vertically disposed cylinder, a piston rod slidable in the cylinder and having a part supporting pedestal on its upper end, a heating chamber above the cylinder into which the part on the pedestal is projected when the rod is elevated, means to supply fluid under pressure to the cylinder to elevate the rod, the rod having an annular groove therein exposed above the cylinder when said rod is elevated, a spring urged block mounted with the cylinder in position to enter the groove, means to positively relieve the fluid pressure after the rod has remained elevated a predetermined time, and means functioning substantially simultaneously with said last named means to withdraw the block from the groove.

ROBERT G. LE TOURNEAU.

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