Early Failures on Frac Rig Transmissions can be Avoided

Quality workmanship, quality parts, and quality service all go hand in hand and can lead to avoiding critical downtime of your well servicing equipment. Early hour failures on a Twin Disc 8500 transmission or 23” torque converters are often the result when you have your repair done by a non-authorized transmission repair shop. In almost all occasions, these transmissions and torque converters are failed due to issues that could have been avoided. To help avoid these problems, we have compiled a list of our findings over the years.

The number one reason for early failures is workmanship. Included in workmanship is taking short-cuts in the repair, choosing to ignore engineering product updates, and cutting corners on bearing inspection/selection.

Missing Engineering Product Updates: A Recipe for Disaster

The product updates are especially critical in high-duty cycle applications such as Well Servicing. Some updates are more critical to product longevity than others; however, you must understand why the factory Engineers chose to make a design change and what the impacts of these changes are in performance. If a transmission repair shop does not have access to all the engineering documents and updated service manuals that go with the product, then they will never understand what caused the failure or how to fix it. Field testing is performed before and after each design change- cutting corners here is asking for trouble.

Taking Short-Cuts in the Repair Process: A Big Problem in High Horsepower Applications

When frac equipment is down, we all know the pressure is on to get the product turned around quickly while avoiding downtime and getting it back into service. However, a small short-cut can lead to much more costly downtime in the long-haul. Here are some common examples of short-cuts taken by local, non-authorized, transmission service providers:

• The internal oil tube brackets are missing, which—to the naked eye— you would never know from the outside of the transmission. However, this can result in a rattling oil tube which will eventually be damaged and result in excess heat due to insufficient lubrication.
• Clutch pack tolerances are not checked and/or correct. Again, you will never know from the outside— everything will seem fine. You might notice slightly harder shifts, but with the kind of environment this equipment is working in, you likely will not notice until it is too late. Wear on clutch plates is very common and each manufacturer calls out certain tolerances that can be measured during the build-up process. Special factory recommendations are sometimes made to add in additional steel plates to close these tolerances and improve shift performance. Short-cutting here will likely result in harsh shifting then early failure or decreased driveline life.

Improper Bearing Inspection and Selection: A Cost--Cutting Mechanism Used by Lower Quality Providers

The cost-cutting repair shop works in some industries but it will burn you nearly every time in well servicing. The difference is: in low-hour, low-duty cycle applications, there is less risk involved and much less torque. But, it is a gamble in frac applications and a BIG ONE. These transmissions see exorbitant hours and are used in very harsh environments with shock loads often applied. The selection of the wrong bearings is a common find; it happens when a repair shop wanting to cut costs works with a bearing house to purchase non-genuine bearings. Often these bearings might have a slight variation which makes all the difference.