Mining shield base lift apparatuses and methods
A longwall mining shield base lift. The base lift includes a hydraulic cylinder having an apparatus for coupling the hydraulic cylinder to the longwall mining shield, a cylinder rod having a first end extending into the hydraulic cylinder and a second end for extending toward ground beneath the longwall mining shield, the second end being threaded axially, and a threaded wear pad threaded onto the cylinder rod. The wear pad includes a plurality of spanner holes for rotating the wear pad with a lever, at least one threaded retaining hole extending axially through the wear pad, and a retaining bolt threaded through the retaining hole until it contacts the cylinder rod.
1. A longwall mining shield base lift, comprising:
a hydraulic cylinder having an apparatus for coupling the hydraulic cylinder to the longwall mining shield;
a cylinder rod having a first end extending into the hydraulic cylinder and a second end for extending toward ground beneath the longwall mining shield, the second end being threaded axially; and
a threaded wear pad threaded onto the cylinder rod, the wear pad having:
a plurality of spanner holes for rotating the wear pad with a lever;
at least one threaded retaining hole extending axially through the wear pad; and
a retaining bolt threaded through the at least one threaded retaining hole until it contacts the cylinder rod.
2. The apparatus of claim 1 , wherein the cylinder rod and the threaded wear pad have complimentary square threads.
3. The apparatus of claim 1 , wherein a plurality of threaded retaining holes extend axially through the wear pad and a retaining bolt is threaded through each retaining hole until it contacts the cylinder rod.
4. The apparatus of claim 1 , wherein the cylinder rod has an axial groove therearound adjacent the cylinder rod threads.
5. The apparatus of claim 4 , wherein the retaining bolt extends into the axial groove in the cylinder rod.
6. The apparatus of claim 1 , wherein the cylinder rod has a plurality of depressions adjacent the cylinder rod threads.
7. The apparatus of claim 6 , wherein the retaining bolt extends into one of the depressions in the cylinder rod.
8. The apparatus of claim 1 , further comprising a gland placed at the juncture of the wear pad and the cylinder rod where that juncture is exposed to extraneous water and dirt.
9. The apparatus of claim 8 , the base lift further comprising a plurality of threaded bolt blocks to each extend into different holes on the underside of a shield canopy to secure, at least in part, the lift to the shield canopy.
10. The apparatus of claim 1 , wherein the wear pad and cylinder rod are constructed of steel and the wear pad is constructed of softer steel than the cylinder rod.
11. The apparatus of claim 10 , wherein pressure on the wear pad is transmitted to the cylinder rod through direct contact to minimize operational load on the threads between the wear pad and the cylinder rod.