An underground excavating system includes a conveyor device which is operative for conveying material away from a mine face, and an excavation roof support device which is operative for supporting the roof of the excavation. A hydraulic cylinder-piston unit is operatively connected to both of the devices and is operative for advancing one of the devices towards the mine face while the other of the devices remains stationary, and vice versa. A guiding arrangement is connected intermediate the control unit and the conveyor device and is operative for guiding the advancing device during its advance towards the mine face. The guiding arrangement includes a pair of elongated support members which are spaced apart of each other and which have one end region located closer to the mine face and another end region located further from the mine face. The guide arrangement further includes a pair of guide sleeve members one at each of the aforementioned end regions. Each sleeve member has wall portions which bound a passage through which the end portions of the support members pass at a spacing relative to each other. The arrangement further includes a pair of insert members respectively connectable to the conveyor device and the control unit. Each insert member is located in a respective passage of the sleeve members and is received between the end portions of the support members for maintaining these end portions at the aforementioned spacing. The insert members and the support members are detachably connected to the sleeve members so as to permit rapid interchange of any of the members which are defective with a replacement member.