A mechanical constant-resistance single prop continuous prop lifting pre-tightening device, structurally composed of a continuous prop lifting device, a pressurizing system, an oil supply line and a monitoring unit. The continuous prop lifting device is a core component, comprising a hydraulic cylinder, a prop barrel clamping sleeve ring and a prop rod clamping sleeve ring. The prop rod clamping sleeve ring is fixedly connected with a piston rod of the hydraulic cylinder by means of a cylinder head seat, and the prop barrel clamping sleeve ring is fixedly connected with a cylinder body of the hydraulic cylinder. With continuous pressurization of the pressurizing system, a cohesion occurs between the continuous prop lifting device and a prop rod, so that the prop rod of a single prop is lifted up to come into contact with a top plate and provide a pre-tightening force.

A mechanical constant-resistance single prop continuous prop lifting pre-tightening device, structurally composed of a continuous prop lifting device, a pressurizing system, an oil supply line and a monitoring unit. The continuous prop lifting device is a core component, comprising a hydraulic cylinder, a prop barrel clamping sleeve ring and a prop rod clamping sleeve ring. The prop rod clamping sleeve ring is fixedly connected with a piston rod of the hydraulic cylinder by means of a cylinder head seat, and the prop barrel clamping sleeve ring is fixedly connected with a cylinder body of the hydraulic cylinder. With continuous pressurization of the pressurizing system, a cohesion occurs between the continuous prop lifting device and a prop rod, so that the prop rod of a single prop is lifted up to come into contact with a top plate and provide a pre-tightening force.

A hydraulic assembly for a mining system is disclosed. The hydraulic assembly may have at least one control valve for controlling a supply of hydraulic fluid to a hydraulic actuator of the mining system. The hydraulic assembly may also have at least one temperature sensor associated with the at least one control valve. The at least one temperature sensor may be configured to measure a temperature of the at least one control valve. In addition, the hydraulic assembly may have a control unit in communication with the at least one temperature sensor. The control unit may be configured to receive the temperature measured by the at least one temperature sensor. The control unit may also be configured to determine that a leakage has occurred in the at least one control valve based on the temperature.

A mine crib from interlocking planks has pair of jack planks on opposite slides of the crib comprising an upper plank 19, lower plank 20 equipped with plates 23 and 24 having screw holes 34, 35 and threaded rod pass through holes 36, 37 and 38 so that threaded rods 39, 40 and 41 may slide through the holes and passing to corresponding cavities 42, 43 and 44 in plank 19. Each rod has a nut 45 and washer 46 so that the nut may be used with an appropriate tool so that as the nuts wound upward along the threaded rods then the jack plank sections 19 and 20 may be jacked apart and be used to preload the crib.