Patent GB-945585-A (GB)
Title: Improvements in or relating to retardation and/or acceleration control of rotary machines
IPC: B66D5/26
Filed: 1962-04-06
Abstract: 945,585. Inertia governors. VANDERBIJL ENGINEERING CORPORATION Ltd. April 6, 1962 [ April 11, 1961], No. 13377/62. Heading G3B. [Also in Divisions B8 and F2] In an inertia governor responsive to retardation and/or acceleration of a rotary member, a first rotary control member 2 is coupled to the machine for rotation in fixed speed relationship therewith and a second rotary or inertia control member 5 is coupled to the machine for rotation therewith through a torsion bar 6 in such a manner that the members 2, 5 rotate in synchronism under constant speed conditions of the machine but under acceleration or retardation are rotationally displaced relative to one another due to the twist in the torsion bar 6-to effect control. In the arrangement shown in Fig. 1 the member 2 is driven by a pulley 4. The first control member 2 has mounted thereon an insert 10 which is adjustably mounted against a spring 15 by a screw 14 and is pressed against the face of the second member 5 by a spring 11. The insert 10 is provided with a port 12 which co-operates with a port 13 in the member 5. Under normal synchronous running conditions a fluid, supplied at a constant flow rate through a line 17, passes through ports 13, 12 to atmosphere and the fluid pressure in the line 17 remains constant. If the member 2 is retarded by the rotary machine the inertia member 5 will twist the bar 6 and will slide on the insert 10 so that the part 13 will be rotationally displaced forwardly of the part 12. The ports 12, 13 are so shaped that displacement during retardation of the machine alters the resistance to fluid flow in the line 17 to cause a rise in pressure therein in proportion to the magnitude of retardation. The alteration in pressure in the line 17 is then utilized by pressure responsive means to control the retardation of the machine if it exceeds a safe limit. Relative movement of the members 2, 5 in the opposite direction due to acceleration of the member 2 causes a drop in pressure in the line 17 to actuate a pressure responsive means to control the machine acceleration if this exceeds a safe degree. In the brake control arrangement for a mine winding engine a drum 19, driven by a motor 30 through a gear box 31 and belts 32, is provided with brake shoes 20 biased towards the maximum braking effort by a spring 21 counteracted by a piston 22 operating in a pneumatic cylinder 23. The apparatus operates as follows. If an operator moves a brake control valve 25 to a "brake on" position a pressure air feed, from a cylinder 24, via a line 26 to the cylinder 23, is closed and exhaust is permitted through a line 27. Retardation of the winding engine causes occlusion of the port 13 so that air is fed to the line 17 from an air cylinder 34, fed by the air cylinder 24 through a suitable throttle valve 35, at a greater rate than it can escape through the ports 12, 13 and consequently the pressure in the lines 17, 17a, 17b rises to a first predetermined value to operate a diaphragm valve 36 in the line 29 to allow to pass to the cylinder 23 to decrease the braking effort exerted on the drum 19 by the shoes 20. If the decrease in braking effort is insufficient the pressure in the line 17, 17a, 17b continues to rise to a second predetermined value and the diaphragm valve 37 in line 27 is closed to shut off the exhaust from the cylinder 23 with the result that the braking effort and the retardation of the drum 19 is is quickly reduced. Reduction to retardation permits the parts 12, 13 to move into alignment so that air escapes from the governor more easily with resulting drop in pressure in the lines 17, 17a, 17b with the subsequent return of the valves 36, 37 to their normal position and the resulting increase in braking effort on the drum 19. The first and second predetermined values can be set within wide limits by an adjustable orifice 38.