This paper presents a new optimization method for dynamic design of planar linkage with clearances at joints. The general consideration is to optimize the mass distribution of links to reduce the change of joint forces. The mass, the center position of mass and the moment of inertia the moving links are taken as the optimizing variables. The objective functions are taken as the changes of the amplitude and direction of the joint forces and they are minimized. The optimized result shows that the magnitude of joint force can be controlled hardly to change and the direction of joint force can be controlled to change smoothly with respect to the crank angle, although the clearances exist at the joints. The link shape can be formed with the optimized variables by using the small element superposing method (SESM) and a design example is given.

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In currently working seismic ACROSS ( Accurately Controlled Routinely Operated Signal System ) transmitters, an unbalanced rotor with large eccentric mass, which generates elastic waves, is supported by roller bearings. With such a type of bearings, bearing losses are so large that heat generation and cooling system become serious problems. To solve these problems, a trial test ACROSS transmitter using hydrostatic gas bearings are designed, made and carried out. The test results show that the hydrostatic gas bearings safely support a largely unbalanced rotor with eccentric mass. In this paper, a new type of hydrostatic journal gas bearings with asymmetric bearing area specially proposed for a largely unbalanced rotor are analyzed and tested. It is shown that hydrostatic asymmetric journal gas bearings have large load capacity for a largely unbalanced rotor and low gas flow rate compared to the conventional hydrostatic symmetric journal gas bearings.

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