Front fork for suspending a front wheel of a motorcycle

A front fork for suspending a front wheel of a motorcycle, comprising

• an outer tube;
• an inner tube slidable within said outer tube;
• means defining adjacent an upper end of said outer tube a working-oil accumulating chamber which contains a body of oil and above the same a body of air, a lower oil chamber adjacent a lower end of said outer tube, and a pressure chamber intermediate said upper and lower chambers and becoming reduced in volume during the expansion stroke of the front fork;
• passage means for providing fluid communication between said chambers, said passage means comprising a passage formed on an outer periphery of said inner tube held in sliding contact with said outer tube, a first port formed in said inner tube for providing fluid communication between said passage and said pressure chamber, a second port formed in said inner tube for providing fluid communication between said passage and an outer periphery of a lock piston disposed on a lower part of said inner tube, and orifices formed in said lock piston and communicable with said second port for providing said damping effect;
• orifice means in said passage means for providing a damping effect;
• means for varying the effective cross-sectional area of said orifice means for thereby adjusting said damping effect;
• and
• means for preventing working oil which is expelled from said pressure chamber into said lower chamber during the expansion stroke of said front fork from becoming mixed with air from said layer in said upper chamber, said means for preventing working oil comprising a hollow rod fitted to a bottom wall of said outer tube and extending upwardly into the inner tube and carrying at an upper end an auxilary piston, said auxilary piston separating said accumulating chamber from said pressure chamber, said hollow rod providing fluid communication between said accumulating chamber and said lower chamber.