Technical Bulletin
Bulletin No: TCH-001-050 Effective Date: 10/31/02 Cancels: N/A Page: 1 of 1
Subject:
Bendix® Tu-Flo® 550 and Tu-Flo® 750 compressors are designed to operate using Bendix D-2 or D-2A
governors to maintain the correct air brake system pressure.
The governor controls when the compressor runs loaded (building air mode) or unloaded (not building
air mode). In the unloaded mode, part of the governor’s function is to apply a controlled amount of
pressure against the unloader pistons in the compressor head.
OVERRIDING THE D-2 GOVERNOR
Tu-Flo 750
D-2A Governor
Use of non-Bendix valves to override (or instead of) the Bendix D-2 governor can cause incorrect
pressure to be applied to the unloader pistons and result in broken compressor inlet valves. Broken inlet
valves may puncture the compressor pistons, forcing compressed air back into the compressor, through
the compressor flange and into the engine crankcase.
The installation of any valve to override the D-2 governor control is not recommended without prior
Bendix approval. We recommend using only genuine Bendix governors.
Reference Documents
SD-01-333 Service Data Sheet for Tu-Flo 550 compressor.
SD-01-344 Service Data Sheet for Tu-Flo 750 compressor.
SD-01-503 Service Data Sheet for D-2 governor.
© 2002 Bendix Commercial Vehicle Systems LLC. Printed in U.S.A. All rights reserved.