US1669402A - Broaching machine - Google Patents

Description

May 8, 1928.

J. HOSKING BROACHING MACHINE Filed June 8. 1921 2 Sheets-Sheet 1 May 8, 1928. 1,669,402

J. HOSKING BROAGHING MACHINE Filed June 8. 1921 2 Sheets-Sheet 2 Hvonnuuc CYL/NLFEF-P. \ba.

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Patented May 8, 1928.

UNITED STATES PATENT OFFICE.

JOHN HOSKING, OF CLAREMONT, NEW HAMPSHIRE, ASSIGNOB TO SULLIVAN MACHINERY COMPANY, A CORPORATION OF MASSACHUSETTS.

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Application filed June 8, 1921.

My invention relates to breaching machines.

An object of my invention is to provide an improved broaching machine. Another object of my invention is to provide an improved broaching machine operative to simultaneously push and pull the broach through the work. A further object of my invention is to provide an improved broaching machine in which the push and pull may be made substantially equal. A further object of my invention is to provide an improved mechanism for simultaneously pushing and pulling upon a single broach and having common control means operative to cause the simultaneous application of the effective forces simultaneously to the opposite ends of the broach. Other objects and advantages of my improved construction will be apparent in the course of the following specification and appended claims.

In the accompanying drawings I have shown for purposes of illustration one form which my invention may assume in practice.

In these drawings,-

Fig. 1 is a plan view with parts broken away of my im roved broaching mechanism.

Fig. :2 is a si e elevation with parts broken away of my improved broaching mechanism.

Fig. 3 is a transverse section on the line 33 of Fig. 2.

Fig. 4 is a detail transverse section through the main controlling valve.

Fig. 5 is a detail transverse section through the auxiliary controlling valve.

Fig. 6 is a diagrammatic view of the fluid pressure controlling mechanism for my improved broaching mechanism.

Fig. 7 is a sectional-view of the relief valve.

It is a well known fact that in practice many breaches are broken for different causes which might have worked with entire satisfaction had it been possible to reduce the strains imposed upon them. For the purpose of reducing the breakage of broaches, I have provided mechanism operative to simultaneously push and pull upon a broach in such manner that the work of moving the broach through the work piece may be substantially equally divided.

For purposes of illustration I have shown my improved broaching mechanism as comprising a traction screw 1 which may be actuswarm. 415,914.

ated by a rotatable nut 1 and mounted upon a usual type of frame 2 and controlled by a manual lever 3 in a well known manner, this lever being operative in the position shown in Fig. 2 to maintain the traction screw stationary and, when moved to the left and right from the position shown in Fig. 2, to effect opposite movements of the screw 1 together with the broach 4 which is fastened in a well known manner to the screw 1. As is usual in screw type broaching machines, the nut which cooperates with the screw r0- tates at a uniform rate which will insure a substantially uniform rate of movement of the broach irrespective of any substantial variations in tool resistance.

Combined with this mechanism is means for imparting a simultaneous push to the rear end of the broach 4, which mechanism is mounted upon a base plate 5 and comprises a cylinder 6 coaxially arranged with respect to the screw 1 and having reciprocable therein, in alinement with said screw, a piston 7 provided with a piston rod 8. The piston rod 8 is provided at its forward end with a cross head 9 movable along suitable guides 10 formed upon the frame 5 and is further provided with a projecting center 11 adapted to engage in a seat in the rear end of the broach 4. To the front and back ends respectively of the cylinder 6 there are connected pipes 13 and 1 through which fluid pressure may be transmitted to the cylinder to effect opposite movements of the piston 7 therein. Liquid under pressure, for example oil, is supplied by a pump 15 whose suction side is connected to a reservoir 16 and which discharges to a receiver 17 and thence to a system of piping leading to the cylinder 6.

A by-pass 18 is controlled by an adjustably loaded relief valve 19 and leads from the receiver 17 back to the storage tank or reservoir 16 whereby the discharge pressure of the pump may be regulated substantially as desired. As stated, a piping system is connected to the receiver 17 which system comprises a relatively short pipe 20 opening into a T 21 from the other two openings of which there lead further pipes 22 and 23. The pipe 22 is controlled by an adjustable pressure reducing valve 2% and beyond said valve discharges into a valve casing 25 in which there is disposed a manually controlled valve 25'. Leading from the casing at points in the same transverse plane, but spaced circumferentially, are a series of three ports, 26, 27 and 28. The passage 26 communicates by way of pipe 29 with the pipe 14 leading to the rear end of the cylinder. The ort 27 communicates by way of pipe 30 with the suction side of the pump, herein with the reservoir 16. The port 28 communicates directly with the front end of the cylinder through the pipe 13. The valve 25' is hollow and its interior chamber communicates with the pipe 22. The valve is traversed by two radially extending angularly disposed passages 31 and 32 which are adapted respectively to cooperate with the ports 26 and 28. Formed in the periphery of the valve is a groove 33 adapted alternately to connect the ports 27 and 28, and 27 and 26.

The pipe 23 communicates with a valve casing 35 in which a valve 35 is rotatably mounted. The valve 35' is likewise of hollow construction and its interior communicates with the pipe 23. A port 36 extends radially from the bore of the valve 35 to its periphery. A port 37 is formed in the casing 35 and connects by a short pipe 38 with the pipe 14. The valve 35 is adapted to be controlled by an arm 39 connected by a link 40 to a projection 41 formed below the ivot of and on the handle 3.

T e parts are so proportioned that when the handle 3 is in the position shown in Fig. 2, that is, with the screw 1 disconnected from its driving mechanism, the valve 35' is in closed position, and the valve 35 is adapted to be moved to a position to connect the ports 36 and 37 upon movement of the lever 3 towards the left to such position as to effect traction upon the breach 4.

From the foregoing description the mode of operation of my improved mechanism will be readily apparent. A work piece X is shown abutting against a suitable abutment 2 formed upon the frame 2 of the traction screw breaching mechanism. When the breach has been passed through the work piece and secured in any well known way detachably to the front end of the traction screw 1, the valve 25 is adjusted to such position as to connect the port 31 with the port 26 and to interconnect the ports 27 and 28 by means of the groove 33. As a result, liquid at a relatively low pressure will be supplied from the pump 15 through the receiver 17, pipe 20, T 21, pipe 22, reducing valve 24, port 31, port 26, pipe 29, and pipe 14 to the rear end of the cylinder 6 and will effect forward movement of the piston 7 at a. slow rate. When the piston 7 has moved sutficiently far forward so as to cause the center 11 to engage the rear end of the breach, the valve 25 will be shifted to the position shown in Figs. 5 and 6, at which time it will be evident that the front end of the cylinder is connected with the discharge line 30 while the rear end of the cylinder, so far as the pipe 29 is concerned, is cut off from pressure. The manual control lever 3 will next be shifted to the left in Fig. 2 in such manner as to simultaneously start the screw mechanism 1 and to move the valve 35' to supply fluid at the full pressure as regulated by the relief valve 19 to the rear side of the piston 7. The breach will accordingly be forced under the combined pull of the traction screw 1 and the push of the fluid in the cylinder 6 through the work piece X. When the breach reaches the end of its travel through the work piece X, the lever 3 will be shifted again to mid-position, cutting off the supply of fluid behind the piston 6 and interrupting the operation of the trac tien screw 1. The valve 25 will then be shifted to a position turned about 45 counter-clockwise from that shown in Fig. 5 in such manner as to connect the rear end of the cylinder with the storage tank 16 by way of groove 33 and to supply fluid at reduced pressure from the port 32 to the port 28 and so to the front end of the cylinder 6. The center 11 will thereupon draw away from the breach 4, allowing the latter to be removed, and the piston 7 will move over to the rear end of its cylinder ready to repeat the breaching operation. After the breach 4 has been removed, the lever 3 will be shifted to the right to cause the screw 1 to feed back to initial position. \Vhen the piston 7 is at the rear end of its cylinder, the valve 25 will again be moved to the position shown in Fig. 5, thereby interrupting the supply of liquid to either end of the cylinder. The broach will be passed through a new work piece and have its forward end attached to the feed or traction screw 1, and then by operation of the valve 25 the center will again be fed up to the breach. The operation as described above will then be repeated.

From the foregoing description, it will be clear that I have provided an improved broaching mechanism in which simultaneously a push and pull may be imparted to a breach. It will further be evident that I have provided means for simultaneously starting the effective push and pull and controlling them by a single member. It will also be clear than the dimensions of the cylinder 6 and piston 7 and the pressure operatingthem will be so proportioned that the push applied by the center 11 will be substantially equal to the pull imparted by the screw and when different materials are used or breaches of different tooth gradations, the pressure must be varied by adjustment of the relief valve in order to bring about substantial equality between the pushing and pulling effects. It will be evident that the power driving the screw may be anywhere between half sufficient to move the breach Ill to suflicient to move it alone, but that the action of the hydraulic cylinder will always be so adjusted as to carry approximately half the work and the piston speed will be originally proportioned to be in excess of the maximum possible speed of movement of the broach by the screw. It will thus be seen that by adjusting the relief valve, it is possible to build up hydraulic pressure great enough so that by itself it could move the broach faster than could the screw nut alone, but it will be obvious that the screw nut would act as an automatic means to limit the rate of broach movement and thereby insure substantially uniform rate of movement therefor, for the nut is driven only at a uniform rate by exterior power and could not be driven faster by greater pressure on the screw. A further advantage of my improved construction arises from the fact that the control maintains the axis of the broach in exact alinement with its direction of movement throu h the work piece, preventing dragging of t e rear end thereof and so avoiding unequal strains and possible eccentric cutting.

\Vhile I have in this application specifically described and shown one form which my invention may assume in practice, it will be understood that this form of the same is used for purposes of illustration and that the invention may be embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. A broaching machine comprising a broach for doing a unit of work, and means when normally operative adapted to subject said broach to a working stress less than the total force required for performing said unit of work including means for placing a portion of said broach under compression and another portion thereof under tension during its working stroke.

2. A broaching machine comprising a broach for doing a unit of work, and actuating means for said broach adapted to subject the same to a workin stress less than that required for performin said unit of work and whose desired maximum rate of movement can be obtained at any point in its path of travel if the resistance to movement is constant including means for placing a portion of said broach under compression and another portion thereof under tension during its working stroke.

3. A broaching machine comprising a broach for doing a unit of work, and means ada ted to maintain a substantially uniform wor ing stress in said broach less than the total force required for performing said unit of work as long as the texture of the material being worked remains uniform including means for placing a portion of said broach under compression and another portion thereof under tension during its working stroke.

4. A broaching machine comprising a broach, and power means adapted to positively maintain a working stress throughout the length of said broach throughout its working stroke.

5. A broaching machine comprising a broach, and means adapted to maintain a substantially uniform working stress throughout the length of said broach during its entire working stroke if the resistance afforded by the material being worked does not vary.

6. A broaching machine comprising a broach, and means for simultaneously subjecting the same to compression and tension stresses during its entire workin stroke and whose desired maximum rate 0 safe move ment can be had at several points in its path of movement if the resistance to movement is substantially constant.

7. A broaching machine comprising a broach, and means adapted to subject the same to predetermined substantially constant compression and tension stresses either separately or combined throughout its working stroke and in one direction of movement.

8. A machine tool having a longitudinal cutter bar with a plurality of longitudinally spaced cutters in rigid relation therewith, and means for subjecting said bar to a sub stantially uniform stress throughout its length and substantially throughout the time of working thereof which stress can be maintained as long as the resistance offered by the work remains normal.

9. In a broaching mechanism, a broach, and power operated means for simultaneouly pushing and pulling the same throughout the working stroke thereof.

10. In a broaching mechanism, a broach, means connectible with the forward end thereof to pull the same, and means adapted to abut the rear end thereof and apply a push thereto, said pushing and pulling means cooperating to force the broach through the work at a substantially uniform rate.

11. In a broaching mechanism, a broach, means connectible to the forward end there of and operable to pull the same, means adapted to abut the rear end thereof and to push the same, and a single controlling member operative to initiate said push and pull simultaneously to force the broach through the work at a substantially uniform rate.

12. In a broaching mechanism, a broach, means connectible to the forward end thereof and operable to pull the same, means adapted to abut the rear end thereof and to push the same, said pulling and pushing means being operative simultaneously to llll) force the broach through the work, and a single controlling member cooperating with both of said mechanisms.

13. A broaching machine comprising a broach, and means including fluid pressure means for maintaining a working stress throughout the length of said broach during its entire working stroke andapart of which is movable therewith.

14. A broaching machine comprising a broach, and means including mechanically operated means for maintaining a working stress throughout the length of said broach during its entire working stroke while the same travels at a uniform rate of speed within a safe working limit.

15. A broaching machine comprising a broach, and means for simultaneously pushing and pulling said broach and adapted to impart a uniform velocity to the same throughout its entire stroke.

16. In a broaching machine comprising a broach, means for pushing and pulling the same either simultaneously or separately and in either case to maintain a substantially constant rate of movement within a safe limit.

17. In a broaching mechanism, a broach. means for pulling said broach, and fluid pressure means for pushing said broach.

18. In a broaching mechanism, a broach, screw means for pulling said broach, and hydraulic means for pushing said broach.

19. In a broaching mechanism, a broach, means for pulling the same, fluid pressure means for applying a push to said broach, and means for adjusting the pressure applied by said fiuid pressure means to said broach.

20. In a broaching mechanism, a broach having a constant rate of travel for a given piece of work, hydraulic means cooperating therewith for effecting operation thereof, and a plurality of controls for said hydraulic means whereby the same may be subjected to different degrees of hydraulic pressure during working of said piece.

21. In a broaching mechanism, a broach, means operative in pulling the same through a work piece, and independently self actuated means for maintaining the axis of said broach in alinement of the direction of pull of said pulling means.

22. In a broaching mechanism, a horizontally disposed broach, means operative in pulling the same through a work piece, and self actuated means for maintaining the axis of said broach horizontal including an abut ment member.

23. In a broaching mechanism, a broach adapted to be moved when cutting in a path making an angle with the vertical, means for applying a force to one end of said broach operative in causing the same to make a cut, and automatic means for guiding the other end of said broach to maintain the axis of said broach in alinement with the direction of said force and adapted to be controlled independently of said other means.

24. In a broaching mechanism, a broach, hydraulic means for pushing said broach through the work during its working stroke, and means adapted to only guide the front end of said broach and maintaining the axis of said broach parallel with its direction of bodily movement.

25. In a broaching machine, a broaching tool, and power operated means for imparting a working stress substantially throughout the length of the same substantially throughout the working stroke thereof including longitudinally movable and rotatable elements adapted to insure a substantially uniform rate of movement of said tool.

26. In a broaching machine, a broaching tool, and power operated means for imparting a working stress substantially throughout the length of the same substantially througlr out the working stroke thereof including an element having only longitudinal movement and a cooperating rotatable element disposed in a plane transverse thereof.

27. In a broaching machine, a broaching tool, and power operated means for simultaneously imparting tension and compression stresses thereto for forcing the broaching tool through the work including an element having only longitudinal movement and a rotatable element directly engaging the same to rause actuation thereof.

28. In a broaching machine, a broaching tool, and power operated means for simultaneously imparting tension and compression stresses thereto for forcing the broaching tool through the work including an element having only longitudinal movement and a rotatable element disposed in a transverse plane and directly engaging the same to cause actuation thereof.

29. In a broaching machine, a broaching tool, and means for imparting tension and rompression stresses thereto including 00- operating mechanically operated means and longitudinally movable fluid pressure operated means.

30. In a broaching machine, a broaching tool, means for imparting tension and compression stresses thereto including elements adapted to have relative and simultaneous longitudinal movement with respect to said tool, and a single member for controlling both of said elements.

31. In a broaching machine, a broaching tool, means for imparting tension and compression stresses thereto including elements adapted to have relative and simultaneous movement with respect to said tool, means for influencing one of said elements, and a single member for controlling both of said elements.

32. In a breaching machine, a broaching tool, means for actuating the same including mechanical and hydraulic means, and means whereby the operation of said hydraulic means may be made dependent upon the operation of said mechanical means.

33. In a broaching machine, a broaching tool, and separate mechanical and fluid prcissure actuated elements for actuating the too 34. In a broaching machine, a breaching tool, separate mechanical and fluid pressure actuated elements for actuating the tool, and means whereby a dependent relation between the same may be had.

35. In a broaching machine, a breaching tool, separate mechanical and fluid pressure actuated elements for actuating the tool, and means whereby a dependent or independent relation between the same may be had.

36. In a breaching machine, a breaching tool, separate mechanical and fluid pressure power generating elements for actuating the same, means whereby a dependent or independent relation between the same may be had, and means for controlling said elements at the will of the operator.

37. In a breaching machine, a broaching tool, separate mechanical and fluid pressure power elements for actuating the same, means whereby a dependent or independent relation between the same may be had, and means for controlling said elements at the will of the operator either one or the other independently or both simultaneously.

38. In a broaching machine, a broaching tool, fluid pressure means for actuating the same, and means automatically maintaining the rate of movement of said tool substantially constant.

39. In a broaching machine, a broaching tool, hydraulic means for actuating the same, and means adapted to control the rate of movement of said tool independently of the hydraulic pressure used.

40. In a broaching machine, a broaching tool, separate hydraulic and mechanical means for actuating the same, and means whereby said hydraulic means is automatically made inoperative upon completion of the working stroke of said tool.

41. In a broaching machine, a breaching tool, cooperating separate mechanical and hydraulic means for actuating the same, and means whereby said cooperation is automatically discontinued upon completion of a predetermined travel of said tool.

42. A broaching machine comprising a breaching tool, and means for actuating said tool including a pressure fluid cylinder and plston and fluid displacement means associated therewith, said actuating means being adapted to impart a predetermined substantial y constant rate of movement to said tool irrespective of variations in tool resistance.

43. A broaching machine comprising a breaching tool, means for actuating said tool including a pressure fluid cylinder and piston, and fluid displacement means associated therewith, said actuating means being adapted to impart to said tool a substantially constant rate of movement within a predetermined fluid pressure limit irrespective of variations in tooi resistance.

44. A breaching machine comprising a broaching tool, means for actuating said breach including a pressure fluid cylinder and piston, fluid displacement means associated therewith, said actuating means being adapted to impart to said tool a substantially constant rate of movement within a predetermined fluid pressure limit irrespective of variations in tool resistance, and means for varying said limit.

45. A broaching machine comprising a broaching tool, and means adapted to impart a predetermined substantially constant rate of movement to said tool irrespective of tool resistance, said means including a pressure fluid cylinder and piston.

46. A broaching machine comprising a breaching tool, means adapted to impart to said tool a predetermined substantially constant rate of movement within a predeter mined fluid pressure limit irrespective of tool resistance, said means including a pressure fluid cylinder and piston, and means for varying said limit at will.

47. A breaching machine comprising a breaching tool, means adapted to impart a predetermined substantially constant rate of movement to said tool irrespective of tool resistance, said means including a pressure fluid cylinder and piston adapted to directly actuate said tool.

48. A broaching machine comprising a broaching tool, means adapted to impart a predetermined substantially constant rate of movement to said tool irrespective of tool resistance, said means including a pressure fluid cylinder and piston adapted to be subjected at least to a part of the tool actuating force, said cylinder and piston being relatively movable throughout the working stroke of said tool.

49. A broaching machine comprising a breaching tool, means adapted to impart a predetermined substantially constant rate of movement to said tool irrespective of tool resistance, said means including a pressure fluid cylinder and piston adapted to be subjected to fluid pressure which bears a definite relation to the force exerted on said tool.

50. A breaching machine comprising a breaching tool, means adapted to impart a substantially constant predetermined rate of movement to said tool in one direction irrespective of variations in tool resistance, said means including a cylinder and piston adapted to be subjected to actuating pressure fluid during such movement, and means for returning said tool to its initial position independently of an actuating fluid.

51. A breaching machine comprising a broaching tool, pressure fluid actuating means therefor adapted to move said tool in one direction. and means for returning said tool to its initial position independently of said other means.

52. In a breaching machine, a breaching tool, means for actuating the same including a hydraulic cylinder and piston, and a pump whose fluid displacement within a predetermined limit is substantially equal to the fluid flow to said cylinder.

53. In a breaching machine, a breaching tool, means for actuating the same including a hydraulic cylinder and piston, a pump whose fluid displacement within a predetermined limit is substantially cqual to the fluid flew to said cylinder, and means for adj usting said limit.

54. In a breaching machine, a breaching tool, a cylinder and piston therein, means for applying hydraulic pressure to one side of said piston during actuation of the tool, and means whereby said. piston may be returned to its initial position Without subjecting the other side thereof to fluid under pressure.

55. In a breaching machine, a breaching tool. and means for insuring a substantially constant rate of movement thereof including a hydraulic cylinder and piston, and means whereby increasing the hydraulic pressure above that required for said constant rate of movement does not necessarily change the rate of movement of the breach.

56. In a breaching machine, the combination of a member for actuating a breaching tool, hydraulic means for driving said member, and a fluid displacement pump for delivering liquid to said means While maintaining a substantially steady advance of the breaching tool at a predetermined rate irre spective of variations in tool resistance or pressure.

57. In a breaching machine, the combination of a tool member, hydraulic means for driving said member, means for delivering of tool resistance.

59. In a breaching machine, the combination of a tool member, hydraulic means for driving said member, a variable fluid displacement pump for delivering a driving liquid to said hydraulic means at a rate corresponding to fluid displacement from the pump, and means to regulate the rate of travel of said member which involves varying the fluid displacement from said pump.

60. In a broaching machine, a breach, means for pulling said breach, and means for simultaneously pushing said breach, one of said means being fluid pressure operated.

61. In a breaching machine, a breach, means for pulling said breach, and means for simultaneously pushing said breach. one of said means being screw operated and both of said means being power operated.

62. In a breaching machine, a breach, means for pulling said breach, and means for simultaneously pushing said breach, one of said means being fluid pressure operated While the other thereof is screw operated.

63. In a breaching machine, a breaching tool, and means for imparting tension and compression stresses thereto throughout its working stroke including cooperating mechanical and fluid pressure operated means.

64. In a breaching machine, a breach, and means for simultaneousely imparting to said breach substantially equal pushing and pulling forces for moving the breach through the work at a substantially uniform rate throughout its working stroke,

In testimony whereof I aflix my slgnature.

JOHN HOSKING.

CERTIFICATE OF CORRECTION.

Patent No. l, 669, 402.

Granted May 8, 1928, to

JOHN HOSKING.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Page 2, line 118, for the word""than" read "that"; page 3, lines and 101, claim 8, strike out the words "the time of"; page 4, line 52, claim 21. for the word "of" first occurrence read "with"; and that the said Letters Patent should be read with these corrections therein that the same may conform to the recond of-the case in the Patent Office.

Signed and sealed this 10th day of July, A.- D. 1928.

(Seal) M. J. Moore. Acting Commissioner of Patents.

during such movement, and means for returning said tool to its initial position independently of an actuating fluid.

51. A breaching machine comprising a broaching tool, pressure fluid actuating means therefor adapted to move said tool in one direction. and means for returning said tool to its initial position independently of said other means.

52. In a breaching machine, a breaching tool, means for actuating the same including a hydraulic cylinder and piston, and a pump whose fluid displacement within a predetermined limit is substantially equal to the fluid flow to said cylinder.

53. In a breaching machine, a breaching tool, means for actuating the same including a hydraulic cylinder and piston, a pump whose fluid displacement within a predetermined limit is substantially cqual to the fluid flew to said cylinder, and means for adj usting said limit.

54. In a breaching machine, a breaching tool, a cylinder and piston therein, means for applying hydraulic pressure to one side of said piston during actuation of the tool, and means whereby said. piston may be returned to its initial position Without subjecting the other side thereof to fluid under pressure.

55. In a breaching machine, a breaching tool. and means for insuring a substantially constant rate of movement thereof including a hydraulic cylinder and piston, and means whereby increasing the hydraulic pressure above that required for said constant rate of movement does not necessarily change the rate of movement of the breach.

56. In a breaching machine, the combination of a member for actuating a breaching tool, hydraulic means for driving said member, and a fluid displacement pump for delivering liquid to said means While maintaining a substantially steady advance of the breaching tool at a predetermined rate irre spective of variations in tool resistance or pressure.

57. In a breaching machine, the combination of a tool member, hydraulic means for driving said member, means for delivering of tool resistance.

59. In a breaching machine, the combination of a tool member, hydraulic means for driving said member, a variable fluid displacement pump for delivering a driving liquid to said hydraulic means at a rate corresponding to fluid displacement from the pump, and means to regulate the rate of travel of said member which involves varying the fluid displacement from said pump.

60. In a broaching machine, a breach, means for pulling said breach, and means for simultaneously pushing said breach, one of said means being fluid pressure operated.

61. In a breaching machine, a breach, means for pulling said breach, and means for simultaneously pushing said breach. one of said means being screw operated and both of said means being power operated.

62. In a breaching machine, a breach, means for pulling said breach, and means for simultaneously pushing said breach, one of said means being fluid pressure operated While the other thereof is screw operated.

63. In a breaching machine, a breaching tool, and means for imparting tension and compression stresses thereto throughout its working stroke including cooperating mechanical and fluid pressure operated means.

64. In a breaching machine, a breach, and means for simultaneousely imparting to said breach substantially equal pushing and pulling forces for moving the breach through the work at a substantially uniform rate throughout its working stroke,

In testimony whereof I aflix my slgnature.

JOHN HOSKING.

CERTIFICATE OF CORRECTION.

Patent No. l, 669, 402.

Granted May 8, 1928, to

JOHN HOSKING.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Page 2, line 118, for the word""than" read "that"; page 3, lines and 101, claim 8, strike out the words "the time of"; page 4, line 52, claim 21. for the word "of" first occurrence read "with"; and that the said Letters Patent should be read with these corrections therein that the same may conform to the recond of-the case in the Patent Office.

Signed and sealed this 10th day of July, A.- D. 1928.

(Seal) M. J. Moore. Acting Commissioner of Patents.

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