May 31, 2021

Classic Failures

Presses are very robust and dependable machines but sooner or later they will have component
failures that are consistent with their design features. Every Press has area’s that fail. After
spending years repairing presses and analyzing how they failed it become apparent that each
Press Manufacturer has components that consistently fail in the same manner, I call these
“Classic Failures”.

The Ajax Manufacturing Company has been building Forging Presses for decades. They are
known for building tough, reliable forging presses. Ajax has used the same basic Main
Gear/Clutch design for over 50 years. Properly maintained it consistently provides the required
torque. But sooner or later this drive will fail in a very predictable way.

This classic failure typically starts with lack of lubrication or improper maintenance procedures.
It is also seen when the clutch inner bearing is replaced and proper installation procedures are
not followed. The Main Gear is supported by two roller bearings. The Inner Roller bearing is a
double cup with two tapered roller bearings and a center spacer. The Outer Roller bearing is a
three-piece straight roller bearing. These roller bearings must be MANUALLY lubricated.

The classic failure first presents itself as increased gear noise. Next an uneven wear pattern is
seen on the main gear teeth and gear backlash becomes tighter on the frame side. The Inner
Roller bearing has lost its proper preload. The lambryth grease seals start to support the frame
side of the main gear. As those mechanical seals wear the gear teeth loose proper alignment.
This also reduces the clearance in the clutch driving splines and the clutch starts to disengage
slower. This creates undo stress on the Brake and starts to cause increased brake maintenance.
The basic clutch design is very robust, and it will continue to operate as it self-destructs from
the inside out. Damage occurs to the Crankshaft, Clutch Drive Pinion, Clutch Driving Plates,
Clutch Friction Plates, and internal splines of the Main Gear. What started as a Roller Bearing
losing its preload turns into major repairs and a very significant amount of down time.
Ajax recommends: “Inner and outer clutch antifriction bearings should be greased at two-week
intervals with a moderate amount of grease. Over greasing will have a detrimental effect on
clutch operation.”

I recommend two ounces of grease per bearing every 100 hours of main motor operation. Also,
remove the Outer Clutch Flange and clutch plates every 2000 hours. Remove any excess grease,
clean and inspect all parts before reassembling. The Main Gear must be properly supported
whenever the Outer Clutch Flange is removed. Under “Normal” operating conditions the inner
and outer roller bearings should be replaced every 20,000 hours of main motor operation.

This Classic Failure starts with a roller bearing that requires a spacer to maintain proper running
clearance and a manual lubrication point that is not easy to access. Many press manufacturers
use this type of bearing set up for flywheels and back shafts. This design requires very little
lubrication and these bearings often last 10 years or more when properly maintained. Regular
maintenance and timely replacement will avoid this Classic Failure and the significant costs
Dave Cooper III
CHP Systems, Inc

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