GB191103107A - Improvements in or relating to the Control of Reciprocating Machinesaws. - Google Patents

Abstract

3107. Wicksteed, G., and Wicksteed, R. Feb. 7. Reciprocating-saw machines. -Relates to reciprocating machine - saws having an hydraulic device for lifting the saw from the work on the return stroke, such as described in Specification 2121/09. The hydraulic device comprises an oil - reservoir E and a casing consisting of a barrel G<1>, pressure chamber I, and cylinder H'. A piston H, controlling the saw frame by means of a connecting-rod H<2>, is slidable in the cylinder H<1>, and a plunger G is reciprocated in the barrel G<1> bv an eccentric on the shaft reciprocating the saw, through a connecting-rod F<1>, a sliding member G<5> and bolt G<6>, the lastmentioned forming a lost-motion device. The reservoir E and pump-barrel G communicate near the delivery end through an opening G<4>, and the pressure chamber I communicates with the cylinder H<1> and the reservoir E through non-return valves G<2>, G<3>. A plug L, provided with a right-angled passage-way L<1> and a T- shaped passage-way L<2>, is fitted in the casing G<1>, I, H<1>. In the plane of the passage-way L<1> are arranged ports J<1>, J<2>, J<3> communicating with the cylinder H<1>, pressure chamber I, and reservoir E respectively. In the plane of the passage-way L<2> are arranged ports J<4>, J<5> communicating with the pressure chamber I and reservoir E respectively. The plug L can be rotated without stopping the saw by a handle or lever arranged outside the reservoir E. When it is in the position (a), Fig. 6, both the passages L<1>, L<2> are closed and the plunger pumps the oil into the cylinder H', raising the piston H and consequently the saw step by step until overflow ports H<3> in the cylinder H<1> are uncovered. When the plug is in position (b), Fig. 6, the pressure chamber I is in communication with the reservoir E through the passage L<2> and ports J<4>, J<5> so that the piston H and saw frame remain stationary at any desired height. When the plug is in position (c), Fig. 6, the pressure chamber I is still in communication with the reservoir E through the passage L<2> and ports J<4>, J<5>, but the cylinder H' is in communication with the reservoir E through the passage L<1> and ports J<1>, J<3>, so that the piston H and saw frame fall, their motion being rendered gradual by a pin-hole plug J<6> inserted in the port J<3>. When the plug is in position (d), Fig. 6, which is the normal position when the saw is cutting, oil is pumped from the pressure chamber I through the passage L<1> and ports J<1>, J<2> and the saw is raised from the work at the end of the cutting - stroke and lowered again at the end of the return stroke. If desired, the lost-motion connexion between the member G<5> and the plunger G may be dispensed with.