... Trundle bearings adopt 6200 and 6303 ball bearings, precision bearing clearance standard, which make the trundles more lubricating, little rolling resistance ... , and quiet. F, Trundle rubber adopts Japanese formula standard. With natural rubber, plus other materials, make the wheel ... deformation and loose. According to Japanese J I S standard B8723 regulations:4, Trundles: Add 3 times of rated ...