GB720925A - Dental or like chair having a seat which can be raised and lowered - Google Patents

Abstract

720,925. Dental chairs. HARTMANN, G., [trading as EMDA, FABRIK ELEKTROMEDIZINISCHER UND DENTALER APPARATE, G. HARTMANN]. April 22, 1953 [May 2, 1952], No. 11106/53. Class 52 (2). In a dental' &c. chair having an actuating lever for raising and lowering the seat by means of an oil-pressure pump driven by an electric motor the actuating lever is arranged so that it has to be raised from the neutral position to raise the seat and to be depressed from that position to allow the oil pressure to discharge and so lower the seat. As shown, the actuating lever is a pedal 15 connected by arms 16 to a sleeve 17 oscillatably mounted on a spindle 18. The sleeve 17 has an offset portion at one end which is engageable with a lug 231 offset from a rocker arm 20 which is biased by a spring 21 to bear with its projection 35 against a fixed stop 22, Figs. 3, 3a, which show the lever and rocker arm in neutral position. To raise the seat the actuating lever 15, 16 is raised until its projection 23 bears against the fixed stop 22, the rocker arm 20 not moving since the lug 23<SP>1</SP> is not engaged by the offset portion of the sleeve 17. The mercury switch 5 mounted on the pivot 30 of a rocker 31 is actuated by means of a finger 32 engaging the plate 33 so starting the electric motor. Releasing the pedal lever 15, 16 allows it to return to neutral position switching off the mercury switch 5 but preventing discharge of the oil pressure. Downward movement of the pedal switch 15, 16 causes the rocker arm 20 to be rocked downwardly by the engagement of the offset portions of the sleeve 17 and the rocker arm. A pin 25 on the rocker arm 20 moves the bell-crank lever 26, 27 anticlockwise so depressing the valve 7 and releasing the oil pressure.