When the track is subjected to alternating contact stress, the large shear stress may cause reciprocating plastic deformation, initiate cracking and expansion, and finally lead to shallow pitting or peeling of the hardened layer, which makes the track and the roller unable to work normally. This phenomenon is called contact fatigue damage. Increasing the shear strength can improve the contact fatigue resistance, the material hardness is high, and the shear strength is also high. Surface hardening treatment of rails and rollers is commonly used in engineering to improve contact fatigue resistance. The determination of the thickness of the hardened layer is essential to ensure that the track and the roller are safe and reliable. If the hard surface layer of the track surface is too thin, peeling of the hardened layer is liable to occur. Therefore, the interface between the hardened layer and the internal base layer should be located at a small shear stress, and the maximum shear stress should be in the hardened layer. Tests show that as the depth of the hardened layer increases, the residual tensile stress caused by surface quenching will increase, and the increased residual tensile stress will accelerate crack propagation and shorten fatigue life. Therefore, under the premise of meeting the requirements of use, the depth of hardening should not be too large. Large-scale hydraulic casting tracks should be made of heat-treated medium-carbon alloy cast steel. The type of steel and heat treatment should be selected according to the strength, toughness and plasticity requirements of the track. The contact surface between the casting track and the roller generally needs to be quenched and hardened to improve the wear resistance of the track and prevent contact fatigue. (Finish)
Achieve high productivity and lower operating costs with the Cat 313D2 L Hydraulic Excavator. Unmatched versatility, improved controllability, easy operation and a comfortable, redesigned operator station help make the 313D2 L an industry-leading performer.
Performance
• The power ful, ef ficient Cat ® C 4.4 mechanical engine of fers up to 14% lower fuel consumption than the model it replaces with no loss of lif ting or digging force.
• The low-pressure fuel system with an electrically controlled governor allows the engine to be more robus t with qualit y fuel.
• Boom and s tick regeneration valves help reduce fuel consumption. • Highly ef ficient hydraulic pumps deliver optimal power to suit general cons truction applications.
• Engine can run on biodiesel up to B20 that meets ASTM 6751 standards.
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