The majority of current Shimano pedals and some pedals by other manufacturers employ a cartridge-style bearing assembly, which is installed pre-adjusted and lubed and which is fitted with an effective seal to keep out dirt. Despite their appearance, these bearings not only can be lubricated and adjusted, but will benefit from regular maintenance.
The bearing type in question may be identified by the castellated plastic sleeve that retains it in the pedal body. The bearing itself comprises a steel tube with a cup-type race machined in each end to house loose balls. The axle has an integral cone at the crank end and an adjustable cone with locknut at the other. Bearing play is adjusted using the cone and locknut.
The tube is a light press fit in the pedal body and, once in place, provides a secure platform for pedal rotation. It is pressed into place and removed using the sleeve, which has a fine left-or right-hand thread depending on pedal side and which fixes the tube laterally in the pedal. A seal on the end of the sleeve runs against the pedal axle.