GB1083082A - Improvements in self-operating mechanisms for retarding the movement of an object down an inclined runway - Google Patents

Abstract

1,083,082. Roller conveyers. ISO-SPEEDIC CO. Ltd. May 31, 1966 [March 1, 1965], No. 8660/65. Addition to 1,024,936. Heading B8A. [Also in Division F2] The wheel or roller 17 of the parent Specification is provided not only with a narrow passage (30), Fig. 4 (not shown), interconnecting parts of a chamber 26 on either side of sun and planet wheels 27, 28 acting as a gear pump, which passage (30) provides a continuous braking effect, but also with a second passage 32, (33), (34), Fig. 5 (not shown), having a throttle valve comprising a ball 38 urged away from its seating (37) by a spring (39). At low rotational speeds the pump pressure differential is insufficient to close the throttle valve so that oil is pumped through the two sub-circuits formed by passages 30 and 32, (33), (34). These subcircuits provide a resistance which increases as the speed increases, part A of the curve in Fig. 7. When the load on the roller exceeds a certain value the pressure differential acts to close the throttle valve so that the second sub-circuit 32, (33), (34) is closed and oil can only flow around the first sub-circuit 30. This introduces a sudden increase in resistance, part B of the curve of Fig. 7. Subsequent increase in rotation speeds increase the resistance according to part C of the curve of Fig. 7. In this way light loads are able to reach a reasonable velocity but appreciably heavy loads are not able to reach an excessive velocity. The passage 30 may be eliminated, the ball 38 reaching a stop before closing the passage 32, (33), (34). Alternatively the high resistance may be provided by the necessary small clearances in the pump. In an alternative embodiment, Figs. 8 to 11 (not shown), a sun-wheel (59) co-operates with an internally toothed rotor (61). Two kidneyshaped slots (63), (64) are interconnected by a sub-circuit consisting of bores (66), (67), (69) and are each fitted with a leaf spring (71) one end of which forms a closure member overlying the entrance to the corresponding bore (66) or (67) but is held away to a limited extent by a screw (74) and by means of a spring (75). In this case the device operates in either direction.