The pulley block on the head of the mainarm can be a combined type pulley block.
所述主臂的头部的滑轮组还可 以是组合式滑轮组。
2
A. Surface Closers: BHMA A156.4; rack-and-pinion hydraulic type with adjustable sweep and latch speeds controlled by key-operated valves and forged-steel mainarm.