Wilwood two pound and ten pound residual pressure valves retain a minimum brake line pressure to help eliminate excessive pedal travel in both disc and drum brake systems. The two pound valve is used in disc brake applications where the master cylinder is mounted below the horizontal plane of the calipers and fluid drain back occurs from gravity and vibration, thereby causing excessive caliper piston retraction and a longer brake pedal stroke. The minimal two pound residual pressure prevents fluid from flowing back without causing the brakes to drag. With drum brakes, a ten pound valve is used to compensate for return spring tension and maintain wheel cylinder sealing in the drums. Residual Pressure Valves are made from billet aluminum and color coded for easy identification. Valves with fittings are supplied with two 1/8-27 NPT to 3/-24 inverted flare female fittings that will fit most domestic 3/16th hard brake lines.
Boat handling expertly under power requires an understanding the propeller effect called [ prop walk or propeller walk ] . To explain how prop walk occurs, the lower blade of a turning propeller rotates in denser water than the upper blade (as water density increases with depth) thus creating a paddle wheel effect. This has a tendency to push the stern sideways in the direction or the propeller rotation. A right-handed or clockwise-rotating propeller tends to "walk" the stern to starboard when moving forwards. The direction of rotation reverses in reverse gear when the yacht is going astern, with the propeller "walking" the stern to port.