Patent GB-1524839-A (GB)
Title: Drilling boom assembly
IPC: E21B15/04
Filed: 1975-09-12
Abstract: 1524839 Drill mounting boom GOSUDARSTVEN PROEKT-KONSTRUKTOR I EXPERIMENTAL INST PO OBOGATITEL NOMU OBORUDOVANIJU "GIPROMASHOBOGASCHENIE" 12 Sept 1975 37650/75 Heading B4C [Also in Division B3] A rock drill boom assembly, Fig. 1, comprises a boom 1 longitudinally extensible by hydraulic cylinder 8 and pivotable in a horizontal plane on column 2 by cylinder 14, Fig. 3, and in a vertical plane by a cylinder 12, and a feed bar 4 pivotably mounted on the end of the boom for movement in a vertical plane by cylinder 9 and in a horizontal plane by cylinder 10. The feed bar carries a "drifter", or rock drill 5 and is movable axially by a cylinder 6 and can be turned about an axis O 2 O 3 , parallel to its own axis, by mechanism 11. To prevent the working end of the feed bar moving away from the rock face (or, more accurately, from a vertical plane) - in use when either (i) the boom is pivoted vertically by cylinder 12 or (ii) pivoted horizontally by cylinder 14, the boom assembly is provided either with (i) a servomechanism 15 for controlling the operation of the boom-extending cylinder 8 or (ii) a servomechanism 17, Fig. 3, for controlling the operation of feed bar-displacing cylinder 6. As shown, the assembly has both mechanisms. The mechanisms are similar in construction and operation, the one, 15, comprising a rod 133, Fig. 8 a hydraulic cylinder 90 mounted slidably on the rod and a servovalve 95 also slidable on the rod, the chambers "h" and "i" of the cylinder 90 communicating respectively with those "f" and "g" of the controlled cylinder 8, Fig. 10 (and Fig. 6, not shown). The servovalve 95 has a body 94 fixed to the piston rod 93 of cylinder 90, and a plunger 132 attached to the rod 133, as shown in Fig. 9, via springs 140, 141 rods 146, 147 and washers 142, 143 engaging abutments on the plunger and bushing 145 which connects rods 146, 147. The plunger allows or prevents communication between fluid supply duct 138 and duct 134 leading to chamber "h" and duct 135 leading to chamber "f" and between ducts 134, 135 and return ducts 136, 137 the relative position of the plunger and body 94 is determined by a connecting linkage 16 connecting body 91 of cylinder 90 to the bearing plate 3 for column 2. The "linkage" 18 of servomechanism 17 connects cylinder 152 to column 2. Cylinder 12 (Fig. 7, not shown) includes a pilot cylinder (52) having chambers in communication with those of cylinder 9 such that "hydraulic parallelism" is ensured (to keep feed bar 4 horizontal). In operation, boom 1 is tilted vertically upwardly by feeding fluid to cylinder 12 by means of distributor 159, Fig. 10. Distributor 163 is operated to feed fluid to duct 138. By virtue of "linkage" 16 cylinder 90 and body 94 move to the right relative to plunger 132 and fluid flows from duct 138 to duct 135 and to chamber "f" to extend cylinder 8. At the same time chamber "h" of cylinder 90 communicates via duct 134 with duct 136 and return line 161. As cylinder 8 extends fluid expelled from "g" flows to "i" in cylinder 90 along line 160 to displace rod 93 to move valve body 94 relative to the plunger 132 which then closes duct 138. The boom may be extended at will and not automatically by disengaging distributor 163 and using distributor 162. A similar operation occurs with the other servomechanism 17.