Pistons And Connecting Rods; Piston Rings; Base Plate/Base Adapter; Cylinder Head - BENDIX TU-FLO 550 COMPRESSOR Manual

PISTONS AND CONNECTING RODS

If the pistons are to be replaced ensure that the correct
pistons are being installed. Note that the pistons for the
Tu-Flo ® 550 compressor are similar to those of other Bendix
compressor models but may be identifi ed by the piston
diameter and the distance to the center of the wrist pin from
the top of the piston as shown in Figure 13.

PISTON RINGS

Check each ring end gap in a cylinder bore before
installation. Place the ring in the top of the cylinder bore
and using the piston, push the ring to the midpoint of the
cylinder bore and check the ring gap. If the end gaps are
incorrect either the wrong repair size has been purchased
or the compressor is worn beyond specifi cation and should
be replaced.
Install the rings on the pistons per the following instructions
starting at the center of the piston and moving outward.
1. Install the spacer and segment rings as follows. Place
the spacer ring (25) in the piston groove, the ends of
the spacer must butt and not overlap. Install the top
segment (24) by inserting one end above the spacer
in the ring groove, 120 degrees from the spacer ends
and wind the segment into position. Install the bottom
segment in the same manner beneath the spacer
making sure the gap is staggered 120 degrees from
both the top ring segment and the spacer end gaps.
Before using be sure both painted ends of the spacer
are visible and butted.
2. Install the compression rings (23) in the proper grooves
with the bevel or "pip" mark (if any) toward the top of
the piston. (Refer to Figure 14.)
Check the ring side clearance of each ring in the piston ring
groove. (Refer to Figure 14.) If the side clearance is too
large, the piston ring groove is worn beyond specifi cations
and the piston must be replaced.
Rotate the piston rings in their respective groove so that
each end gap is at least 90 degrees from the previous
ring's end gap.
Lubricate the wrist pin (22) and wrist pin bushing in the
connecting rod with engine oil. Assemble the upper portion
of the connecting rods and the pistons with the wrist pins.
Insert the wrist pin buttons (28) in the ends of the wrist pin.
Lubricate the pistons and rings with engine oil. Using a ring
compression tool return the piston to the cylinder bore.
Turn the crankshaft so that one of its connecting rod journals
is in the downward, center position. Install the crankshaft
journal bearing segments (38) on the connecting rod (37)
and connecting rod cap (39). Tighten the connecting rod
bolts (40) evenly and torque to 150 - 170 inch pounds.
Install the other connecting rod and piston in the same
manner. It is recommended that new connecting rod cap
screws be used.
Before replacing the cylinder head on the crankcase
ensure the correct pistons have been used by turning the
crankshaft one complete revolution such that each piston
moves to its maximum upward stroke. At the maximum
upward stroke position each piston should move to the top
of the crankcase. If the piston does not approach the top
of the crankcase the piston is incorrect and if not replaced
could result in compressor damage.
BASE PLATE OR BASE ADAPTER
Position the base plate or base adapter gasket (20) on the
crankcase and install the base plate or base adapter (21)
as marked before disassembly. Tighten the six cap screws
(22), securing the cast iron base adapter evenly to a torque
of 175-225 inch pounds for base plate or cover in a crossing
pattern after fi rst snugging all 6 screws.

CYLINDER HEAD

Place the cylinder head gasket (19) and cylinder head
on the compressor crankcase and install the six cylinder
head cap screws. Snug the cylinder head cap screws prior
to torquing the cap screws to 300-360 in. lbs. in a cross
pattern. Retorque the unloader cover cap screws to 170-
225 in. Ibs.

FINAL COMPRESSOR ASSEMBLY

Install all crankshaft keys making certain to support the
crankshaft to avoid bearing damage. Install the crankshaft
nut where applicable. When installing drive couplings or
gears, do not exceed 120 foot pounds torque on the
crankshaft nut.
Use covers, plugs, or masking tape to protect all ports if
compressor is not to be installed immediately. Protect the
ends of the crankshaft against damage by wrapping with
masking tape or friction tape.

TESTING REBUILT COMPRESSOR

In order to properly test a compressor under operating
conditions, a test rack for correct mounting, cooling,
lubricating, and driving the compressor is necessary. Such
tests are not compulsory if the unit has been carefully
rebuilt by an experienced person. A compressor effi ciency
or build up test can be run which is not too diffi cult. An
engine lubricated compressor must be connected to an oil
supply line of at least 15 P.S.I. pressure during the test and
an oil return line must be installed to keep the crankcase
drained.