Patent GB-629398-A (GB)
Title: Improvements in or relating to medical practice chairs
IPC: A61G15/02
Filed: 1946-12-31
Abstract: 629,398. Medical chairs. RITTER CO., Inc., Dec. 31, 1946, No. 15481/48. Convention date, July 2, 1946. Divided out of 629,345. [Class 52 (ii)] A chair for use in medical practice comprises a seat frame, a back rest pivoted thereto, locking means for securing the back rest in pivotally adjusted positions with an operating lever located on the back rest for pivotal movement therewith, further locking means are also provided for pivotal movement of the back rest in intermediate e adjusted pivotal positions. As shown the chair comprises a seat frame 49 pivotally mounted by means of trunnions 47, 48 on a head 46 of a column 43 mounted for both vertical and rotary movement in a housing 42 having an electric motor 41. The seat frame 49 is provided at the rear with a box-like portion 50 in the walls 51 of which is provided a spindle 52 pivotally supporting the base 53 of the back rest. The base 53 has an upstanding post 54 upon which is slidable a member 55 having at its rear dovetailed grooves in which slide a member 56 to the end 58 of which is pivoted at 59 the back frame of the back rest 60. A further slidable portion 61 for the head rests is provided. A downward extension 63 of the base 53 of the back rest is provided with a block 64 having wedging ends 64 which wedge rollers 67 against roller races 68 on the walls 51 of the portion 50, springs 70 pressing the rollers 67 into wedging position and so locking the back rest to the seat frame in upright position of the chair. Mounted on the base 53 by means of a pivot 79 is an operating lever 78 having a slot 81 in which seats the upper end of a plate 82 the other end of which engages the hooked end of an arcuate member 86 pivoted on the pivot 52. Forward movement of the lever 78 moves the member 86 anti-clockwise and causes the ends 88, 89 of arms to press the rollers 67 out of wedging engagement and so permits pivoting movement of the back rest. The latter may now be lowered until it is in substantial alignment with the seat. Pivoted at 79 in a slot in the end of lever 78 is a latch 92 which is normally pressed by a spring 93 against a finger 90 of the lever to keep it in rearward position. When the lever 78 is operated to release the wedging action of the rollers 67 and the back frame is lowered to horizontal position the end 95 of the latch snaps into the notch 96 and so locks the back frame in its lowered position forward movement of the lever 78 being required to release the latch end 95 from the notch 96 to permit the back rest to be elevated to normal position again. The back rest may be locked in intermediate tilted position by means of a lever 110 associated with one of the arm rests. The arm rests are provided with frames 97 which are pivoted to the seat frame by means of trunnions 102 having springs 103 to counterbalance the back rest. One of the trunnions 102 is provided with a sleeve keyed thereon which sleeve has a pin operating in an inclined slot formed in a cap rotatable on the sleeve by means of the lever 110 causing the cap to move endwise inwardly and so moving a thrust rod 114 longitudinally. The other end of the rod 114 moves a lever 117 against the action of a spring 120 and frees a spindle 127 normally pressing on a split block 122 to lock it about a spindle 125 depending from the seat frame and so preventing movement of arm rests in relation to the seat frame until the lever 110 has been operated. Any intermediate tilted position of back rest in relation to the seat frame may be secured and locked thereby. Specifications 629,345, 629,399, 629,400 and 629,401 are referred to.