| 摘要 |
PURPOSE:To keep off any possibility that steerage might be impossible due to a malfunction in each of various valves by installing an unloading valve which is selected by the inserting-drawing operation of a lock pin for a rear- wheel locking means via a cord body. CONSTITUTION:A booster cylinder 31, steering rear wheels 3 via a steering knuckle arm 25 consists of a cylinder 33, a piston slidably housed in this cylinder and a selector valve 37, and it is provided with a sensing cylinder 47 is addition. A lock lever 69 is clamped to the steering knuckle arm 25, and a lock pin 79 of a single acting cylinder 73 with a formation spring is inserted into a lock hole formed in this lock lever 69, thus the rear wheels 3 are made lockable. In this case, there is provided an unloading valve 101 which is selected to either of transfer positions 101a, 101b synchronously with inserting or drawing operation in or from a lock hole 71 of the lock pin 79 via a cable 103 as a cord body, and when this valve is selected to the transfer position 101a, both first and second oil passages 55, 57 are made so as to be interconnected to each other. |
