Patent GB-270715-A (GB)
Title: Improvements in or relating to means for the hydraulic transmission of power
IPC: B23B47/22
Filed: 1927-05-03
Abstract: 270,715. National Automatic Tool Co., (Assignees of Galloway, R. M.). May 4, 1926, [Convention date]. Eccentric-actuated pumps; stroke, varying.- In means for reciprocating machine parts hvdraulicallv means Actuated bv the movement of the parts control the speed. The invention is described with reference to a multiple drilling machine; having a head 3, Fig. 1, operated by a piston in a cylinder 24, to opposite ends of which pipes 28, 29 lead from a pump unit P of variable output driven by a motor M, the drills 4 being rotated by a common shaft 5 sliding in a bearing 6 and driven from the motor M by gearing. The output of the pump, and consequently the direction and speed of movement of the drill head are controlled by a valve V, operated by a shaft 41 having a gear segment 45, Fig. 2, slidable thereon meshing with a rack carried by the head. The rack has a second set of teeth meshing with a gear segment 52, on a shaft 53, which is acted on by a spring 57 so as to tend to force the rack inwardly towards the pillar 2, and has a shoulder 63, Fig. 11, adapted to engage with abutments t carried by spring-pressed plungers 59 - - 62. In order to start the head movement, the shaft 53 is rotated by a lever 67 in opposition to its spring to move the rack to its outermost position, the valve V being thereby so set that a rapid downward movement of the head takes place, which continues until the plunger 59 is moved in opposition to its spring by contact with an adjustable stop 91, to free its abutment t from the shoulder 63. The rack then moves inwardly until the shoulder engages the abutment on the plunger 60, the valve V being thereby so set that the feed is continued at a slower rate. A second slow speed is obtained when another stop 93 trips the plunger 60. Subsequently, a stop 95 trips the plunger 61, 62 to allow the rack to move to its innermost position, where the valve is so set as to obtain a rapid upward movement of the head. At the end of the upward movement, the gear segment 52 on the shaft 53 is moved by contact with a stop 100, to move the rack outwards until the shoulder 63 engages with the abutment t of the plunger 62, when the valve is in its neutral position. Varied cycles of operations may be performed by coupling the plungers in pairs, by setting the stops so that adjacent plungers are depressed simultaneously by using a stop acting on two plungers at once, and by providing an extra stop acting on the segment 52, so that rapid downward movement is resumed when desired. Further, all the plungers may be retracted simultaneously by means of a hand lever 89, in order to stop the down stroke at any time and cause the return of the head to its uppermost position. The pump unit comprises a pump C, Fig. 29, of constant output, and a variable dislacement pump X, the eccentricity of the latter being controlled by means comprising a stop x', Fig. 28, a spring plunger x<8> and Hydraulic pistons x<10>, x<11> having adjustable stroke-regulating check nuts x<14>. When the valve V is in the neutral position d, as shown in Fig. 18 liquid passing from the pump C finds no outlet through the pipe 30, but returns through the pipes r<12>, r<16> and valve R to the reservoir 200; pipes 33, 34 leading to the cylinders of the pistons X<10>, X" also communicate with the reservoir at this time through the pipe 31, so that the pump X is at zero eccentricity. To secure the rapid downward movement, the valve V is moved to the position a, as in Fig. 14. Pressure from the pump C then passes through the lines 30, 32, 33, 34, that passing through lines 33, 34 setting the pump X so that it delivers its maximum output into the line 28, and that passing through 32 acting on a piston r<5> to set the valve R, so that liquid from the pump C passes through the lines r<11>, r<12> to 28. The first slow speed is obtained by moving the valve V to position b; pressure is maintained in the lines 33, 34 so that the pump X still delivers its maximum output but since the line 32 connects with line 31. centring springs return the valve R to its neutral position, so that the output of the pump C is returned to the reservoir. When the valve V is moved to position c, line 33 is put to exhaust, pressure remaining in the line 34, so that the output of the pump X may be decreased. When the valve V is in position e, a rapid upward movement is obtained by liquid from the pump C passing through the line 29.