Metal/Metal type spherical bearing
Metal/Metal type spherical bearings require periodic re-lubrication, both to replenish the used grease and to flush out contamination. Metal/Metal types are suitable for applications where static load applies. Aircraft landing gear is a typical ideal situation for this type of bearing. The high impact load is experienced (take off and landing) when the bearing is stationary, while the extension and retraction movement only takes place during light load.
- Heat treated bearing steel & 440C stainless steel for balls, 410 stainless steel & 4130 alloy steel for races
High static load capacity, suitable when minimum deformation is required under heavy load. - Al -Bz race
High seizure resistance under oscillating load and limited lubrication, however, they only have 1/2 the load carrying capacity of steel race. - Be-Cu ball with 17-4PH race
They can provide good performance under high load and slow fluctuation velocity when sufficient lubrication is supplied. - Loading slot and fracture type race spherical bearing
No swaging required and therefore they can provide high hardness. They have high load carrying capacity and abrasion resistance. Hydraulic cylinder is one of the typical applications of this type. Very high temperature applications may require nickel alloy steels such as STELLITE®, INCONEL®, and A286, which can provide high temperature creeping resistance. As they are often applied under impermissible temperature of grease, solid lubrication such as dry film or silver plating are substitutable.
PTFE type spherical bearing
The PTFE Liner is bonded to the inner diameter of the race. The PTFE Liner acts as a lubricant and therefore no other lubrication is necessary. Thus they are eminently suitable to apply where re-lubrication is impractical or impossible. More over, as they don't require any lubrication, they are effective to lower the maintenance cost. They perform well under slow fluctuation velocity and oscillation load. Therefore PTFE type can induce the difficulties of metal/metal type such as high friction, seizure, fatigue destruction and fretting on the fluctuating surface.
2 Piece Rod End Bearing
Consist of ball and body. The body is directly swaged on the ball. Ball material is usually high cold-working performance steel (303 stainless steel), these bearings have lower load carrying capacity compared to 3 Piece Rod End Bearings. However their economic cost and uncomplicated production makes them suitable for commercial applications with spacious construction. They do not require any lubrication, and in addition, stainless materials (303 for bodies, 440C for balls) enable the anti corrosion characteristics.
3 Piece Rod End Bearing
Consist of a spherical bearing staked into the Rod End body. They provide high strength, as main body material is chrome molybdenum steel (hardness 35HRC, tensile strength 980N/mm2{100kgf/mm2}). Material selection of spherical race is depending on applications and therefore, they can bear severe requirements.
Ball Rod End
Figure 3: Ball Rod End
Construction consists of several balls in rows interfacing with body inner surface. Although having less load carrying capacity than plain bearings, lower torque can be achieved by reduced contact area. Self-alignment is also possible with these types. Ideal applications are aircraft controls and robot linking areas. (Figure 3)
Sealed Type Spherical bearing
Figure 4: Sealed type Spherical Bearing
Constructed with seals fixed with seal retainers on chamfering of spherical edges. Seals prevent ingress of foreign objects or dust and strengthen the life of bearings. Silicon and synthetic rubber are used as seal materials with 304 stainless steel as retainer. Seal retainers are electron beam welded to race edges. Sealed type bearings are originally developed for aircraft applications, however, they are now widely applied in construction machinery and automotive field. (Figure 4)
Minebea provides a wide range of custom designed bearings in addition to the standard bearings presented in this catalog. There are numerous customer applications which demand custom-designed bearing assemblies to meet a wide range of enviromental and operating conditions.
Minebea is staffed with an experienced sales and engineering group, ready to assist our custmors with special design requirements. Some of the special products manufactured by Minebea include loader slot bearings, rod and linkages, sealed spherical bearings, miniatures as well as very large swaged bearings.
Please consult Minebea's sales staff or engineering department for any of these special needs.