Heavy duty needle roller bearing is a kind of high capacity bearing with small sectional height . it can operate very flexibly even with the light alloy bearing seat due to its high hard outer ring.there are two series:metric and inch series.both of which are structured with retainer,full needle and sealing types. besides, the entity bushed needle roller bearings are divided into two kinds:that with inner ring and without ring.the center shaft is used as rolling body tray for those without inner ring so that its size is even smaller.