Abstract: An overtravel indicator for a piston received in a cylinder having an end wall toward which the piston moves includes an elongated indicator rod slidably mounted through a dielectric bushing in the end wall. A conductive garter spring is compressed between the indicator rod and a groove in the cylinder end wall. An electric circuit including an electrically operated indicator is connected for completion through the indicator rod, end wall and garter spring. In an inward armed position of the indicator rod, dielectric material carried by the rod is interposed between the rod and garter spring for opening the electric circuit. In an outward operated position of the rod, a conductive surface on the rod engages the garter spring to complete the circuit and operate the indicator.

Abstract: A piston overtravel indicator for indicating overtravel of a piston from a rest position adjacent one end of a cylinder to working positions displaced from the rest position toward the other end of the cylinder. The indicator includes an elongated indicator rod slidably extending through a hole in the other end of the cylinder and having an inner rod end located within the cylinder adjacent the working positions of the piston. Overtravel of the piston beyond working positions causes engagement of same with the inner rod end for moving the rod outwardly through the hole. The indicator rod has a circumferential groove adjacent the inner end thereof for cooperation with a yieldable abutment extending into the hole for preventing complete outward displacement of the indicator rod through the hole.

Abstract: A hydraulic device includes a rod connected with a piston for limited axial movement relative thereto for opening a passage through the piston while pulling on same and closing the passage while pushing on same. The rod and piston are connected by a separable coupling including cooperating coupling parts formed integrally on the rod and piston for connecting and disconnecting the rod and piston by relative lateral movement therebetween.