GB704290A - A method for testing the mechanical strength of coal and a device for carrying out the method - Google Patents

Abstract

704,290. Testing physical qualities of coal. DEUTSCHE KOHLENBERGBAU-LEITUNG. Jan. 10, 1952 [Jan. 18, 1951; May 17, 1951], No. 784/52. Class 106 (2) The mechanical strength of coal is measured by forming a bore hole in the coal and determining the force required to drive a pin into the wall of the bore hole. In Fig. 1 a body b, in a bore hole a, carries a probe pin g on the frontal face of a plunger e, the plunger e being movable outwardly of the body b by oil pressure acting through a pipe h. The pressure required to cause a required penetration of the pin g into the coal is indicated on a pressure gauge q, further outward movement of the plunger e uncovering a pipe k allowing the compressed oil to return to an oil container p. By closing the pipe h and supplying the pressure medium through a pipe i to act on the plunger e in the reverse direction, the plunger can be moved backwards and the pin g brought within the circumference of the body b. A packing piece s, which holds the plunger e in the body b, can be unscrewed to allow the plunger e to be exchanged. The probe pin g is also exchangeably attached to the plunger e. Additional plungers l<SP>1</SP>, l<SP>11</SP> in the body b are arranged to be pressed by oil pressure against that side of the bore hole wall which is opposite to the side at which the probe pin g projects, thus ensuring a snug and immovable contact of the testing device with the wall of the bore hole. In a second embodiment, Fig. 5, the body b is securely fixed in the bore hole a by turning a screwed spindle i, through a handle j, the resulting axial movement of the spindle i being adapted to cause an outward movement of opposed clamping jaws g. When the body b is securely located in the bore hole a, a further turning of the spindle i causes it to abut against a capsule o from which a pin d projects, increasing pressure on the capsule o presses the pin d into the coal and the force applied therefore is read off on a pressure gauge f connected to the capsule. After terminating the movement, the spindle i is turned back again, whereupon the jaws g return to their initial position within the body b under the action of springs h. The pin d may be arranged to move in a direction at right angles to the axis of the body b.