Needle bushes consist of a thin, heat treated outer ring formed from accurately controlled sheet steel encasing a set of needles.
Bushes may have a full complement of needles retained in the outer ring by their ends or by grease; others have the needles retained in a cage which is prevented from moving laterally in the outer ring. These bearings which occupy very little radial space are particularly economical to use and possess a high load capacity, relative to their size. They should be selected in preference to other bearings when conditions of mounting and operation permit.
When needle bushes are used without an inner ring and the needles rotate on a shaft of suitable hardness, they occupy minimum space and therefore provide a very satisfactory solution.
Maximum load capacity is obtained with a shaft hardness under the needles of at least 58 HRC. A lower hardness is acceptable if loads and required life permit. Hardened inner rings can be supplied for most Nadella needle bushes. They remove the necessity to harden the shaft and enable the
bearings to accept full load capacity.
All needle bushes are normally supplied unlubricated (except where a special grease has been requested). However, they are coated with a thin film of grease to prevent corrosion.
