| 摘要 |
<p>513,264. Wrenches. PARKER, L. F. March '7, 1938, No. 7131. [Class 61 (iii)] [Also in Groups XXI and XXX] A tunnelling machine comprises a shield annulus with a rear plate 2 carrying an annular track formed of opposed U-plates 22, 22x, a carriage 23 being carried by rollers within the track and moved on the latter by a motor through worm gearing 28 and rack and pinion gearing 21, 25; the carriage carries a swinging bracket 33 supporting a universally-pivoted bracket 36 with a pivoted member 37 carrying a head 37x adapted to hold the nuts of the lining bolts 38 while the bolts are turned.</p> |
