| 摘要 |
PURPOSE:To obtain a proper braking force corresponding to the weight of a load by raising a push up member as a wheel shaft rises relative to a body frame under the heavy load, and activating a control valve by means of a rod spring. CONSTITUTION:In no load operation, a wheel shaft 4 is moved downwards to a great extent away from a body frame 1 by the resilience of a leaf spring 2 so that a rod spring 1 restrains the control force on a rear wheel 3 without pushing the piston 12 of a control valve 10. In light load operation, the rise of the wheel shaft 4 relative to the body frame 1 is greater due purely to the sag of main spring 7, and thus the pressing force of the bar spring 16 on the piston rapidly increases so as to provide controlling force on the rear wheel 3. On further increase of load, the main spring 7 acts together with a subspring 8 which results in the lack of control force on the rear wheel 3. At that time, the rod spring 16 is pushed by means of a push member 20 so that the push force is increased. As a result, even if operated under heavy load, a proper control to the rear wheels 3 can be controlled properly. |
