MAGSEAL 101

Rotary face seal that utilizes magnetic attraction force to positively mate the optically flat seal faces. Magnetic attraction force variation is kept to a minimum as it controlled by the internal air gap for maximum service life. Magnet is magnetized through the diameter so that the magnetic circuit is closed at the outside diameter of the seal case. It is directionalized (anisotropic) for maximum magnetic energy and stability. Components are freely mounted on elastomers that prevent seal face distortion and are positive secondary seals. They secure the magnet in the housing or retainer, provide rotation of the seal case and dampen system vibrations. Axial shaft movement is taken up by the rolling action of the seal case o-ring within the groove. Radial shaft movement can be accomplished increasing the diametrical clearances to ensure positive seal ring contact. O-ring quality in accordance with AS 871 for positive secondary seal. Temperature range is limited by the elastomer Special designs available for high pressure or pressure reversal or large axial shaft movement. DESIGN INFORMATION

1.The magnet ring is magnetized through the diameter so that the magnetic circuit (flux) is closed at the outside diameter of the seal case. The flux lines extend radially from the magnet’s outside diameter to the outside diameter of the seal case and this magnetic circuit results in only minor stray flux. 2.The magnetic attraction force applies a mechanical load on the seal case mating face (seal ring) to ensure positive contact when there is no applied system pressure. 3.In order for any ferrous debris to be attracted into this magnetic field it must pass though this field due to either oil flow or gearbox windage. The magnetic field strength degrades to less than 3 gauss at a distance of.5 (12.7 mm) for a typical gearbox MAGSEAL. Any debris that becomes entrapped in this magnetic field will be retained and therefore prevented from migrating to the primary mating face. 4. The seal case o-ring friction drive is designed so that a significant force (greater than the magnetic attraction force) is required to slide the o-ring along the shaft.

REVERSE TAPER DESIGN TAPER IN HOUSINGTAPER ON MAGNET Compression force from o-ring provides a resultant axial force to seat the magnet squarely against the shoulder O-ring roll or twist during installation may prevent the magnet/mating ring from seating squarely against the bore shoulder thus putting the mating face out of square relative to the axis of rotation (shaft). Seal leakage as a function of shaft speed is indicative of an out of square mating face. STRAIGHT HOUSING BORE

HIGH PRESSURE MODEL 20 Higher pressures require that the seal ring mating face be in the balanced condition. Balanced condition is achieved by making the seal ring contact area (seal ring OD to seal ring ID) greater than the area exposed to pressure (seal ring OD to shaft balance diameter).

Pressure greater than P2 or 30 PSI max less than P2 Pressure 30 PSI max greater than P1 or less than P1 PRESSURE REVERSAL P2 P1 Magnet is retained in the housing with a non-magnetic retaining ring. The seal case drive o-ring contacts an external shoulder. The hydraulic force from the system pressure acting on the seal ring mating face is always positive (closing the seal face) regardless of which side has the higher pressure.

AXIAL SHAFT MOVEMENT.010 SPECIAL MAGSEALSTANDARD MAGSEAL LARGE AXIAL SHAFT MOVEMENT UP TO.05 WITH LARGER CROSS SECTION O-RING AND SPECIAL GROOVE WIDTH ALLOWS O-RING TO ROLL WITHIN GROOVE WHILE PROVIDING POSITIVE ROTATION AND SEAL FACE CONTACT.

LOW UNIT (FACE) LOAD WITH MINIMUM VARIATION DUE TO INTEGRAL MAGNET ATTRACTION FORCE, REDUCES POWER CONSUMPTION, HEAT GENERATION AND THEREFORE INCREASES SEAL LIFE. EFFICIENT HEAT DISSIPATION DUE TO THE USE OF MATERIALS WITH A HIGH COEFFICIENT OF THERMAL CONDUCTIVITY AND CONSTANT OIL CIRCULATION FROM THE ROTATION OF THE SEAL CASE. MOUNTED ON ELASTOMERS THAT DO NOT ADVERSELY AFFECT SEAL FLATNESS AS WELL AS DAMPING SYSTEM VIBRATIONS THUS ELIMINATING SEAL FACE CHATTER AND WEAR. HIGH UNIT (FACE) LOAD (30%-50% GREATER) WITH LARGER VARIATION DUE TO COMBINATION OF INTEGRAL SPRING AND OPERATING LENGTH TOLERANCE, INCREASES POWER CONSUMPTION, HEAT GENERATION, AND THEREFORE REDUCES SEAL LIFE. SPRING CAVITY TRAPS OIL THAT CAN TURN INTO COKE WHICH COMPROMISES THE EFFECTIVENESS OF THE WAVE SPRING AND THE O-RING DUE TO THE LARGE MASS OF CARBON WHICH HAS A LOW COEFFICIENT OF THERMAL CONDUCTIVITY. MATING RING IS CLAMPED WHICH MAY ADVERSELY AFFECT FLATNESS AS WELL AS TRANSMITTING SYSTEM VIBRATIONS DIRECTLY TO THE SEAL FACE THUS RESULTING IN SEAL FACE CHATTER AND WEAR. SEAL DESIGN / PERFORMANCE COMPARISON MAGSEAL STAMPED CUP MECHANICAL SEAL

TYPICAL MAGSEAL MILITARY AND COMMERCIAL AIRCRAFT APPLICATIONS Missile and Small Engine Main Shaft Engine and Air Frame Accessory Gearboxes Main Transmissions Intermediate and Tail Rotor Gearboxes Auxiliary Power Units Starter Motors and Pneumatic Starters Generators and Alternators Air Drive Units and Air Turbine Motors Constant Speed Drives Fuel Pumps and Controls Hydraulic Pumps and Motors Wing Flap and Slat Actuators