Design Standards

Design Standards
Shafer^® roller bearings are designed and manufactured to meet specific application needs. Each individual bearing meets all loads and motions requirements of our customers. Our bearings meet design requirements in a wide range of sizes, configurations and materials.

PSI^® designs and manufactures precision aerospace bearings that meet and exceed the high performance requirements for flight controls, landing gear systems, and power plant controls, levers and mounts. These bearings are available in a wide variety of configurations and material combinations to match the needs of system designers.

Roller Bearings

Shafer roller bearings are available in single- and double-row configurations, in a wide range of designs that include annular, links, rod-end and special configurations. Materials used in the manufacturing of Shafer bearings can be selected to meet bearing performance requirements over a wide range of conditions.

Shafer roller bearings provide the designer with:
     • Low friction in operation (.001 - .002)
     • High-load carrying capabilities
     • Internal self-alignment to accommodate installation misalignment or in-flight deflections
     • Minimal system backlash due to small internal bearing clearance

Single-row bearing capabilities include:
     • Predictable bearing life over the life of the aircraft
     • Minimal to zero wear rate over the life of the aircraft
     • Internal misalignment

Double-row bearing capabilities include:
     • Predictable bearing life over the life of the aircraft
     • Minimal to zero wear rate over the life of the aircraft
     • Internal misalignment
     • High-load capacity in radial and axial directions
     • Minimal initial free-play, including preloaded assembly
     • Stainless steel bearings provide superior corrosion resistance

All of our double-row bearings can be ordered in the following configurations:
     • Standard roller complement, non-precessing
     • Standard roller complement, precessing
     • Full roller complement, non-precessing
     • Full roller complement, precessing

The Shafer “precessing” roller set is a Shafer-patented feature that causes the rollers to continuously rotate around the bearing, thereby distributing lubricant, prevent fretting and wear, and prolonging bearing life in oscillatory applications.

All bearings can also be manufactured from CRES/CREN materials, offering superior corrosion resistance. Please contact our engineering department to discuss the specifics of your application to ensure optimum cost, performance and reliability.

Ball Bearing
Shafer provides double-row, rod end style ball bearings per standard SAE AS21151, AS21152, and AS21153.

Link Style Roller Bearings
Shafer roller bearings provide a variety of link style bearings to meet various application needs. The links, which offer the same high quality bearing functionality as Shafer’s line of double-row annular bearings, can be either a cartridge design or integral design. They are offered in the following configurations:
     • Standard roller complement, non-precessing
     • Standard roller complement, precessing
     • Full roller complement, non-precessing
     • Full roller complement, precessing

Typically made of a carburizing grade steel similar to AISI 9310, all links are designed to meet the structural fatigue requirements of the eye and shank. They are ideal for locations where space is restricted, such as wing-tips and leading and trailing edges. Shafer roller bearing links provide the designer with:
     • Low friction in operation
     • High-load carrying capabilities
     • Internal self-alignment to accommodate installation misalignment or in-flight deflections
     • Minimal system backlash due to small internal bearing clearance

Links can be designed in a variety of sizes and configurations to meet your application needs. Please contact our engineering department to discuss the specifics of your application situation to assure optimum cost, performance, and reliability.

Special Rod Ends
Because of the demanding needs of the aerospace industry, numerous special bearing configurations have been designed. Applications include:
     • Military aircrafts
     • Commercial helicopters
     • Flight control actuators

Special rod ends can be designed to meet a variety of sizes, configurations and loads. Shafer also offers manufacturing per customer source controlled drawings (SCD). Please contact our engineering department to discuss the specifics of your application situation to assure optimum cost, performance, and reliability.

Split Ball Bearings
A "split ball" bearing design involves an axial separation of the ball into two halves, which allows the individual halves to be inserted axially into the outer race and then rotated into alignment within the outer race to eliminate the need for the "ball entry window." Manufacturing expertise and control are crucial for precisely matching the "ball halves" so that ball sphericity and uniform final assembly clearance are maintained, allowing the design to function properly in the application.

By eliminating the ball entry window, a split ball bearing design provides:
     • Equal axial load capability in either direction
     • More total bearing area
     • Higher-load capacity
     • Higher bearing stiffness

Split ball bearings are used in secondary flight control systems, such as:
     • Leading edge slats
     • Trailing edge flaps
     • Fixed end of a primary flight control actuator

A split ball bearing should not be installed where clamping on ball is required. The split ball design comes in a standard series P2A6500 and countless custom designs. Please contact our engineering department to discuss the specifics of your application situation to assure optimum cost, performance and reliability.

Split Race Bearings
A "split race" bearing design typically involves an axial separation of the outer race, eliminating the need for the "ball entry window" found in the slotted entry design (although circumferential "split" designs are also manufactured). Manufacturing expertise and precise machine control are crucial for matching the "outer race halves" to retain the sphericity required to allow the bearing design to function properly, i.e., accept ball motion and ball misalignment.

Designers use and prefer split race designs because the split race design provides:
     • Larger total available bearing area
     • High-load capacity
     • Ease of installation and replacement
     • Equal axial load capabilities against either side of the bearing

Split race bearings are used:
     • Where the overall bearing size is too large for swaged bearing design
     • Where high-load capacity is required
     • Where high impact loading is present
     • Where high radial bearing stiffness is required

The split race design comes in a standard series and countless custom designs. Please contact our engineering department to discuss the specifics of your application situation to assure optimum cost, performance and reliability.

Slotted Entry Bearings
The unique two-piece design of the slotted entry bearing features a ball with a spherical race to accommodate misalignment. The outer ring or rod end body has an entry window to allow insertion or removal of the ball. This design feature allows the ball to be fitted to the outer member after all manufacturing operations are completed. This design yields a higher strength outer race than formed or swaged bearing designs, and makes ball replacement easiersince the entire bearing assembly doesn't need to be removed from the aircraft.

Fast, Easy Assembly of Slotted-Entry Bearings

     1. Ball and outer race prior to assembly
     2. Ball is inserted into slotted-entry
     3. Ball shown partially rotated in race
     4. Final assembly with ball fully indexed in race to operating position

Designers use and prefer slotted entry designs because they:
     • Reduce weight of the bearing and related hardware and structure
     • Allow for design flexibility of bearing materials
     • Provide unique bearing configurations and lubricants to meet the application needs
     • Reduce service turnaround times, with "on wing" replacement of the ball
     • Reduce overall maintenance part cost
     • Provide higher bearing reliability
     • Provide the flexibility to select materials that meet a high temperature application environment

Applications include:
    • Landing Gear - Main and nose gear, struts and drag braces with high impact loads. Severe environmental
      exposure and compact design needs can be met with the configuration, material and lubrication system
      flexibility.

• Flight Control Systems - The desire for minimum space and weight, coupled with high loads, make slotted-entry
bearings the best choice for pivoting applications in spoilers, flaps, and slat applications.

   • Engines and Power Plants - The high temperature capability of slotted entry bearings make them the logical
   economical choice for engine mounts, thrust reverses, compressor and nozzle actuators, hot section support
     links and engine duct supports.

Self-Lubricated Liner
Rexlon^® is a polymeric composite self-lubricating material designed for annular bearings, straight and flanged bushings, self-lubricating track roller bearings, and other load carrying, moving components that require low friction and low wear performance.

Rexlon is approved to many industry standards such as:
     • SAE AS81934
     • SAE AS81820
     • Boeing BACB28AZ, AY, AV, AZ, BB, BC, BE, BG
     • Lockheed Martin JFE specifications

Applications include:
     • Airframe secondary controls, aircraft structure, doors and interiors
     • Engine compressor control systems
     • Industrial machinery including butterfly valves and toggle mechanisms

Special Assemblies
Shafer roller bearings can be designed and manufactured to meet unique specifications:
     • Bore sizes up to 10"
     • Internal design variations that eliminate fretting corrosion failures in service
     • Improved sealing features to reduce the effects of corrosion
     • Assembled pre-load torque or reduced internal clearance
     • Grooved, chamfered or retaining ring mounting configurations simplify installation

PSI slotted entry and split ball bearing concepts can be designed and manufactured to meet unique specifications:

     • Wide variety of configurations beyond the typical annular and rod end styles
     • Unique material choices to meet a wide range of application requirements
     • Simplified installation features
     • Titanium material and coating enhance performance and reduce weight
     • Replaceable ball feature reduces total life cycle cost

Application areas include:
Landing Gear Bearings
     • Material and coating flexibility
     • Housing locking features
     • Corrosion resistant

Control System Bearings
     • Reduced system backlash
     • Meets minimum space requirements
     • Reduces size of associated hardware
     • Sealed designs available
     • "On Wing" ball replacement for PSI bearings

Power Plant Bearings
     • High strength material
     • High temperature capacity
     • Vibration resistant

New Technology	Flight Control Actuators	Airframe Structures	Aircraft Doors	Landing Gear
Helicopters	Engine & Gearbox	Tooling	Industrial & Race Cars	Design Standards
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