Heavy Duty Balanced Opposed Compressors - Ariel Corporation

For Models: JGH:E:K:T Section 4 Part Replacement
Torsional Vibration Detuner Installation on Crankshaft
Torsional vibration in reciprocating compressors is a critical consideration. To avoid resonance at natural
frequencies in a given application, a qualified torsional vibration analyst working closely with the packager,
driver manufacturer, and Ariel may determine the drive train requires torsional detuning.
Depending on torsional vibration analysis (TVA) results, the compressor crankshaft may be equipped
with or require the addition of torsional vibration detuners. A torsional vibration detuner is a donut
shaped weight that installs centered on the crankshaft spreader section. Four-throw crankshafts
have one spreader section, while 6-throw crankshafts have two referred to as “Aux End” and “Drive
End”. Detuners add mass in the appropriate amount and location to change the crankshaft natural
frequency and avoid resonance at operating speed. A given application may require one or more
detuners. Detuners are sized specifically for the compressor and application, and custom-bored for
installation on a specific compressor crankshaft spreader section. Do not order or install detuners
unless specifically required by the TVA report. Improperly tuned compressor packages can
cause catastrophic failure, major property damage, and personal injury.
When detuners are required, contact the Ariel Response Center and request Ariel Engineering Reference
ER-42 "Determining Detuner Inside Diameter".
CAUTION: Detuner parts are heavy. Ariel recommends at least two people perform several
of the steps below to avoid personal injury or equipment damage.
To install torsional vibration detuners on Ariel crankshafts:
1. Verify the correct number, type, and mounting location of
detuner(s) for the specific application. Ariel, the driver manufacturer,
the packager, and the torsional analyst cooperatively
develop this information. The analyst provides a detailed location
in the TVA report.
2. A finished detuner has a custom-finished bore with identification
stamping. The stamping includes part number, the
instruction "Mount this face toward coupling" on both halves,
final bore dimensions, the words “Aux End” or “Drive End” for
crankshafts with two spreader sections, and frame serial number
(or crankshaft serial number and nominal crankshaft diameter).
Verify this information is on the detuner and that it
correlates with the compressor and crankshaft. If this information
is in question or missing, contact Ariel before proceeding.
Detuners are not interchangeable for use on other crankshafts,
including replacement crankshafts.
3. Remove Capscrews and discard the two shims located
between the joints of the new detuner.
4. Clean each detuner part thoroughly to remove any dirt or foreign
material.
5. Remove crankcase top cover.
6. Wipe crankshaft spreader section clean and dry.
Remove shim.
Remove shim.
3. Identification
Stamping
4. Eyebolt Hole
FIGURE 4-42 Detuner - Typical
3/11 PAGE 4-37
2
3
1
1. Capscrew
2. Bolt Head
Notch
4
1 2
7. If possible, use an overhead crane to handle detuners. For easy hoisting, install a forged steel
eyebolt in the threaded hole on the outside diameter of the detuner near the Bolt Head Notch
(see Fig. 4-42). If a crane is unavailable, use two people to lift and position the detuner halves
during installation.
8. Lower one detuner half onto the top of the crankshaft spreader section. Use extreme care to
avoid nicking or scratching the crankshaft. If not using a crane, take care to prevent personal