| 摘要 |
PURPOSE:To keep off a shock due to too much effectiveness in a brake, by making an extent of braking force commensurate to a speed variation so as to act on in time of deceleration in a running motor. CONSTITUTION:When a feeding quantity from a hydraulic pump P to a running motor M is throttled by a directional control valve V, additional rotational frequency of the running motor M drops to some extent. At this time, with inertial force acting on the running motor M, pressure in a feed-discharge circuit 1a drops whereby pressure in both feed-discharge circuits 1a and 1b becomes identical with each other so that a selector valve K is selected to a neutral position, thus pressure oil in a pressure oil chamber UA is discharged to a tank T and braking force gets operating. On the other hand, after rotational frequency of the running motor M has dropped, drive of the running motor M by pressure oil out of the pump P is reopened, and the selector valve K is selected to a selecting position K3 so that braking force of braking devices B and B is released. |
