Abstract: A safety interlock valve with two flow passages, which in one position allows flow through the flow passages and blocks flow between them, and in another position blocks flow through the flow passages and allows flow between them. The safety interlock valve can be used in hydraulic systems such as power tongs.

Abstract: A safety interlock valve with two flow passages, which in one position allows flow through the flow passages and blocks flow between them, and in another position blocks flow through the flow passages and allows flow between them. The safety interlock valve can be used in hydraulic systems such as power tongs.

Abstract: A safety interlock valve with two flow passages, which in one position allows flow through the flow passages and blocks flow between them, and in another position blocks flow through the flow passages and allows flow between them. The safety interlock valve can be used in hydraulic systems such as power tongs.

Abstract: A safety interlock valve with two flow passages, which in one position allows flow through the flow passages and blocks flow between them, and in another position blocks flow through the flow passages and allows flow between them. The safety interlock valve can be used in hydraulic systems such as power tongs.

Abstract: An apparatus for shutting off the hydraulic supply of a power tong when the door is opened comprises, in part, a ring gear and cage assembly having a throat. The ring gear and cage assembly are driven by a motor having a hydraulic supply. A door is mounted on a pivot on the ring gear and cage assembly for movement to open and close the throat. A cable is secured to the door at a point that is offset from the pivot. The cable extends through a sleeve to a valve end of the cable. A valve at the valve end of the cable has a valve housing and is operable by movement of a valve control to disengage the hydraulic supply from the motor. The valve end of the cable is connected to the valve control and the sleeve is connected to the valve housing.

Abstract: A power tong with a cable operated door jammer valve for shutting off the hydraulic supply of a power tong when the door is opened.

Abstract: A power tong system, comprising a frame having a rear support and a front support, the front support comprising a first front leg and a second front leg; and a power tong mounted in the frame with the power tong extending transversely between the first front leg and the second front leg, the first front leg and the second front leg forming a guide preventing transverse motion of the power tong while allowing vertical movement of the power tong. The system is also preferably provided with a backup tong. The sides of the power tong are preferably provided with rollers to prevent friction between the power tong and the guide. In a second power tong system, a load cell assembly is provided in which a load cell is linked by a series of links to the power tong such that movement by the power tong in either of two transverse directions loads the load cell.