AGMA 92FTM2-1992 pdf download.Face Gear Drives: Design, Analysis, and Testing for Helicopter Transmission Applications.
The idea of torque split is illustrated in fig. 2. Pig. 2a shows an alternative version of the torque splitting by two spiral bevel pinions. a and 6, designed as one rigid body. Fig. 2b shows the second version of the split of torque when a single spur (or helical) pinion is in mesh with two (acegears The advantage of the face-gear version is that the sarue transmitted power results in a reduced load on the bearings in comparison with the spiral bevel version shown in fig. 2a. A second advantage is the pinion is a conventional spur (or helical) gear compared to a complex spiral bevel design with two pinion..
The general configuration of the MDHC/ Lucas ART de sign is illustrated conceptually in fig. 3. There are two engines rated at 2500 HP each which combine to drive the rotor shaft with 5000 HP. The transmission is designed to carry 3000 HP per side for a one engine inoperative condition. Power flow, from the engine through an overrunning positive-engagement clutch to a spur pinion, which is lightly restrained radially. The spur pinion drives a downward- facing face-gear and an upward-facing face-gear. The face gear shafts terminate in spur pinions, which drive a large combining gear. The hub of the combining gear is attached to the sun gear of a high contact ratio planetary gear set where the carrier is the output member and is attached to th. rotor shaft. A small pinion is driven at the aft side of the main combining gear This pinion drives another face-gear mounted on the NOTARTM (notail rotor) driveshaft, which leads aft directly to a NOTAR fan.
The concept of torque split appears to be a significant development wherein an input spur gear pinion drives two face- gears arranged to provide an accurate division of power. This division greatly reduces the size and weight of the corner- turning hardware as well as the size and weight of the next reduction stage The predicted payoff is greatly reduced weight and cost compared to conventional design.
The pinion which serves the two face-gears is a conventional spur gear with an even number of teeth. If the spur gear were rigidly located between the two lace-gears, precise torque splitting would be very unlikely. The spur gear has a free-floating mount which allows self-centering between the two face-gears. The effect of normal manufacturing inaccuracy on torque split will be compensated by automatic relocation of the input pinion to its balanced position as long as compliant support ii provided for the front end of the pinion shaft. It will be shown analytically (see next section) that precise torque splitting (with ±1.0%) will take place.AGMA 92FTM2 pdf download.