A wear pad for a longwall mining shield base lift. The wear pad includes at least one spanner hole for rotating the wear pad with a lever, at least one threaded retaining hole, and a retaining bolt threaded through the retaining hole until it contacts a cylinder rod to which the wear pad is to be attached.

A method for removing a hydraulic support for solid filling coal mining includes digging a support removing channel (3) in a coal body (2) in front of the hydraulic support (1), and laying a support removing track (4), then removing the hydraulic support from a coal conveying gateway (11) to a track gateway (5), temporary supporting is carried out by matching a single supporting column with a n-type steel beam before each hydraulic support is removed. A supporting roof is reinforced in time by means of erecting a crib (13) and grouting after each hydraulic support is removed, three grouting pipelines (12) are laid after the supports of the whole work surface are removed, and grouting is carried out in the whole finishing cut space. The roof of the support removing space of the work surface is stable so that the hydraulic supports on the work surface of solid filling coal mining are ensured to be safely and efficiently removed.

Mining systems include a continuous miner; a movable roof support; a roof bolter; and a flexible conveyor train positioned with its front end located under the roof support and extending underneath the roof bolter.

An equipment system for a self-retaining mining method mainly comprises a transition support, an end support, a following support, and a fast-retracting support. Working face gateroads do not need to advance in mining, and a coal mining machine may be used to cut a neat coal wall at the end of a district. The entry rib is automatically formed after roof caving, thus forming a gateroad in a re-mining process. The coal mining machine is under digital control when its end cuts the coal, automatically enabling the end to laterally cut the coal wall to form a vertical straight line, which is used as the entry rib of the gateroad. A scrapper conveyor works in coordination with an arc-shaped coal grabbing plate of the coal mining machine to clean up float coal at the end as much as possible.

A pin retaining assembly for an advancing ram includes a retention plate and a retainer. The retention plate includes two oppositely facing surfaces and a channel with a notch between the two surfaces. The retainer includes a main body, a pin receiving slot, and at least two flanges. The main body is configured to slide into the notch of the channel and extend through a surface of the retention plate. The pin receiving slot has an open mouth through an end of the main body. A first flange extends from one end of the main body along a surface of retention plate and a second flange extends from another end of the main body along another surface of retention plate. The flanges retain the main body of the retainer in the first notch from moving in a direction defined by a longitudinal axis of the pin receiving slot.

A float-swing hydraulic support, including a top beam, shield beam, elevating frame, base, adjusting jack, two float hydraulic columns, base raising unit, advancing unit, face guard unit, telescopic beam unit, hydraulic control valve block, and a valve block support. The columns are between the top beam and base, with upper ends ball-hinged to the top beam and lower ends ball-hinged to the base; the telescopic beam unit is in the front end of the top beam, and the face guard unit is hinged to the beam unit; the upper end of the shield beam is hinged to the top beam, the lower end is hinged to the upper end of the frame; the upper end of the jack is hinged to the shield beam, the lower end hinged to the base; the ends of the advancing unit are hinged to a scraper conveyor and the base, respectively.

A float-swing hydraulic support, including a top beam, shield beam, elevating frame, base, adjusting jack, two float hydraulic columns, base raising unit, advancing unit, face guard unit, telescopic beam unit, hydraulic control valve block, and a valve block support. The columns are between the top beam and base, with upper ends ball-hinged to the top beam and lower ends ball-hinged to the base; the telescopic beam unit is in the front end of the top beam, and the face guard unit is hinged to the beam unit; the upper end of the shield beam is hinged to the top beam, the lower end is hinged to the upper end of the frame; the upper end of the jack is hinged to the shield beam, the lower end hinged to the base; the ends of the advancing unit are hinged to a scraper conveyor and the base, respectively.

A ventilation method for a high gas working face based on alternating intake and air return in a mine gallery is provided. In this method, an isolated island working face is divided into several sections along a strike direction. A coal pillar is alternately set as a conventional section and a gas-drainage section. Opposite coal pillars in the two mine galleries within the same section are respectively used as the conventional section and the gas-drainage section. Two mine galleries on both sides of the isolated island working face are alternately used as an intake gallery and a return gallery. The coal pillar at the side of the mine gallery as the return gallery is the gas-drainage section. A gas-drainage hole communicating a goaf is provided in the gas-drainage section, so that gas in the goafs at two sides of the isolated island working face can be extracted alternately.

A pin retaining assembly for an advancing ram includes a retention plate and a retainer. The retention plate includes two oppositely facing surfaces and a channel with a notch between the two surfaces. The retainer includes a main body, a pin receiving slot, and at least two flanges. The main body is configured to slide into the notch of the channel and extend through a surface of the retention plate. The pin receiving slot has an open mouth through an end of the main body. A first flange extends from one end of the main body along a surface of retention plate and a second flange extends from another end of the main body along another surface of retention plate. The flanges retain the main body of the retainer in the first notch from moving in a direction defined by a longitudinal axis of the pin receiving slot.

A ventilation method for a high gas working face based on alternating intake and air return in a mine gallery is provided. In this method, an isolated island working face is divided into several sections along a strike direction. A coal pillar is alternately set as a conventional section and a gas-drainage section. Opposite coal pillars in the two mine galleries within the same section are respectively used as the conventional section and the gas-drainage section. Two mine galleries on both sides of the isolated island working face are alternately used as an intake gallery and a return gallery. The coal pillar at the side of the mine gallery as the return gallery is the gas-drainage section. A gas-drainage hole communicating a goaf is provided in the gas-drainage section, so that gas in the goafs at two sides of the isolated island working face can be extracted alternately.