Friction wedge design optimized for high warp friction moment and low damping force

A method of designing a rail car truck having a bolster, a pair of side frames and a damping system for relative bolster/side frame movement using a side spring supported friction wedges, for optimized lateral warp friction moment and low damping force includes the simultaneous equations:

• Fw W . E = - P 2 · ( cos ⁢ ( θ ) + μ 2 ⁢ w · sin ⁢ ( θ ) ) ( μ 1 ⁢ w ⁣ · cos ⁢ ( θ ) + μ 1 ⁢ w · μ 2 ⁢ w · sin ⁢ ( θ ) + μ ⁢ ⁣ 2 ⁢ w ⁢ · cos ⁢ ( θ ) - sin ⁢ ( θ ) ) · 2 · a · w w [ b · ( a + w w ) ] V c . W . E = 2 · μ 1 ⁢ d · P · ( cos ⁢ ( θ ) - μ 2 ⁢ d · sin ⁢ ( θ ) ) ( - μ 1 ⁢ d ⁣ · cos ⁢ ( θ ) + μ 1 ⁢ d · μ 2 ⁢ d · sin ⁢ ( θ ) + ⁣ μ 2 ⁢ d · cos ⁢ ( θ ) + sin ⁢ ( θ ) )
• where:
• θ is the angle defined between the vertical and sloping surfaces of the friction wedges and P is the side spring force;
• FwW.E. is the required warp friction force—worn—empty;
• μ2w is the slope warp coefficient—max:
• μ1w is the column warp coefficient—max;
• a is the bearing centers;
• b is the wheelbase;
• ww is the wedge width;
• Vc,/W.E is the maximum compression damping force per suspension—empty;
• μ1d is the column damping coefficient;
• μ2d is the slope damping coefficient.