SAE AIR 853A:2001 pdf download

SAE AIR 853A:2001 pdf download

SAE AIR 853A:2001 pdf download Disconnect Systems, Accessory Drive Shaft
1 . SCOPE:
This document defines the functional requirements of basic types of disconnect devices used in airborne accessory installations.
1 .1 Purpose:
The purpose of this report is to provide to accessory manufacturers general design concepts for accessory drive shaft disconnect devices.
There are no referenced publications specified herein.
Disconnect devices in present military and commercial service were designed to meet requirements of each engine accessory installation. It is not considered feasible to establish a standard for such systems.
3.1 Basic types of disconnect devices used in airborne accessory installations:
a. Jaw clutch
b. Extractable shaft, mechanically (solenoid operated) or thermally energized
c. Spring clutch
d. Severed section
4.1 Actuation of the disconnect system may be operated remotely, such as from the flight control compartment by manual, electrical or other means such as automatic control. Also, the actuation may be accomplished thermally within the accessory.
4.2 Means for detecting and displaying an impending malfunction of the driven accessory should be provided for remotely actuated disconnect systems. Means presently in service are:
a. Differential oil temperature
b. Excessive oil temperature
c. Pressure-sensing
d. Speed or frequency-sensing
e. Excessive generator temperature
f. Excessive drive temperature
4.3 Positive disengagement of the accessory input shaft from the power-source output shaft should be accomplished.
4.4 A separate power source should not be required to decouple the accessory from the input shaft. Any force on the mating shaft during decoupling shall be within the limits defined for that drive.
4.5 Disconnect should occur at or near the accessory input spline.
4.6 Adequate lubrication should be provided for disconnect designs which keep an accessory input portion of the device rotating after a disconnect is performed.
4.7 Resetting should be accomplished only when power source is static on the ground.