GB552540A - Improvements in adjustable chairs for dental and like purposes - Google Patents

Abstract

552,540. Hydraulic machines; valves. SMITH, R. A. (White Dental Manufacturing Co., S. S.). Feh. 10. 1942, No. 1737. [Classes 69 (ii) and 135] [Also in Groups XIV, XXXI and XXXV] A dental &c. chair adapted to be raised by hydraulic means is carried by a yoke 105, Fig. 4, at the top of a post 101 guided solely by rollers 93 to telescope within a member 69 itself guided solely by rollers 54, Fig. 11, to telescope within a member 29, which is bolted to the top of a liquid reservoir 7 forming part of a base 5 fitted with rollers 16 for rotation of the chair about a fixed base 1. The moving cylinder 150, Fig. 5, of the hydraulic machine is connected at its outer end at 153 to the member 69 and movement is communicated to the post 101 by a sprocket chain 117 passing over wheels 119, 120 on the member 69 and carrying a lug 116 to engage the post. Adjustment of the chain is provided at the fixed ends 142. A spring pin 111 at the bottom of the post 101 takes the shock of the lowering of the seat. Hydraulic pressure is derived from a compressor 215, Fig. 8, driven by an electric motor 250. Oil or other liquid is drawn from the reservoir 7 through a strainer 246 and delivered past a check valve 221 to a conduit 207 connected with the bore of a hollow piston 173, Figs. 5 and 7. A dome 227 is provided with a screw vent 230, and the cylinder 150 is fitted with a screw vent valve 162. After the cylinder has reached its upward limit a relief valve 401 is lifted by a foot 397 of a lever actuated either by a pedal or automatically by a trip lever 303, Fig. 4. The valve rests on a thrust ball 400 and has a removable strainer 413. A drip trough 285, Fig. 8, located below the check valve has a lip discharging into the oil reservoir.