Safety control device for mine hoists and the like

摘要

235,288. Logan, H. H. March 10, 1924. Dash-pots.-In safety-control apparatus for mine hoists of the kind in which a member connected to braking means is released upon excessive speed and at the ends of the wind and the movement of the member is controlled by a dash-pot that is cutout on an overwind, the movement of the dash-pot mechanism is controlled by one passage during the main run and is freed near the ends of the wind by the opening of a normallyclosed by-pas passage by cam mechanism geared to the hoist. As illustrated, a weighted arm, which applies the brake, is connected to the piston of a dash-pot 5, which in addition to a small orifice 24 in the piston has ports 7, 8 leading through hollow trunnions to a valve. During the main run a rotating member 17 of the valve prevents direct communication between the passages 11, 12 leading to the ports, leaving the orifice 24 as the sole means of communication between the upper and lower sides of the piston. In the event of an overwind, one of two cams geared to the hoist, operates a lever to rotate the valve member 17. This establishes direct communication betwen the passages 11, 12 to a greater or less extent, depending on the amount of overwind, and correspondingly frees the piston for rapid descent. When the weighted arm is raised by hand for re-setting, a by-pass 20 furnished with a one-way ball valve 21 operates to permit ready pasage of the fluid from the upper to the lower side of the piston. Specification 152,466, [Class 78 (v), Winding and paying-out apparatus &c.], is referred to.