Disassembly and Reassembly
29
Installation
Thermo King employs a tapered joint to secure
the drive coupling or drive pulley to the
compressor shaft. This has two advantages: first it
prevents any looseness that might occur as when
using a sliding fit on a shaft. The second
advantage is that when torqued properly the
friction between the two tapers can be used to
drive the compressor under most loads.
A key is used in the tapered joint to guarantee
proper positioning of the coupler to the
compressor, and to the engine or drive pulley.
Using a key can also prevent slippage between the
taper surfaces in case of extreme shock loads. If
the tapers are allowed to slip, galling of the
surfaces occurs. Galled surfaces make
disassembly difficult, and reassembling galled
parts will not assure proper alignment.
Keyways are cut with a tool which leaves a radius
at the end of the keyway. If the key being installed
is pushed onto the radius at the end of the keyway,
the taper will not seat properly and the coupling
will wobble. This causes stress to be put on the
crankshaft and reduces its life. Make sure keys are
of the correct length to fit entirely in their
respective keyway prior to installation.
The following procedure should be used to install
a compressor coupling onto the compressor shaft.
1. Clean the compressor shaft and taper and the
tapered bore of the coupling with a solvent
that leaves no oily residue, such as naphtha,
lacquer thinner, brake cleaner or the like. The
solvent must be nonchlorinated.
2. Inspect both mating surfaces for burrs,
oxidation and other surface imperfections.
Dress with crocus cloth if necessary and
reclean as required.
NOTE: Do not sand or lap the tapered area as
component fracture may result.
3. Using no lubricants, set the coupling on the
crankshaft and align the keyway using the
Keyway Tool (P/N 204-972). Insert the
tapered end of the tool into the keyway and
gently move the coupling on the shaft while
pressing the tool into the keyway. This will
align the keyway in the crankshaft with the
keyway in the coupler.
Figure 9: Keyway Tool P/N 204-972
4. Remove the Keyway Tool and check the fit of
the new key. It should fit into the keyway with
a light press fit requiring only a minimum of
light tapping. If the key does not fit properly,
remove the coupling and inspect the keyways
and key for burrs or other problems. Recheck
the fit as shown above.
5. When the key fits properly, remove the
coupling from the crankshaft and apply a very
thin even coating of blue Loctite 242 to the
back one third of the taper for the 1.0 in.
diameter crankshaft. Do not use Loctite on the
taper for the 1.187 in. diameter crankshaft
taper because it makes it very difficult to
remove the coupling later.
CAUTION: Use a puller to remove the
drive coupling or pulley from the
crankshaft. Puller (P/N 204-139) or puller
with handle (P/N 204-991) are available
for use on compressor couplings with
threaded holes. DO NOT use a hammer to
pound the coupling or pulley off. This will
damage the compressor.
CAUTION: If you are assembling a used
coupler or crankshaft and the tool does
not fit easily there is a problem with one of
the keyways! Do not remove the coupler
and place the key in the crankshaft keyway
and then drop the coupler on. If the tool
does not fit, the key will not fit, and it will
hold the taper in the coupling off the taper
on the shaft. Check both keyways for burrs
or corrosion. A key can be coated with fine
lapping compound and used as a lapping
tool to clean the keyways. Clean the key
and keyway with solvent before final
installation.
AGA333
