Known Issues:

It’s well known throughout the industry that MEC vessels contain several engineering issues drastically degrading the mechanical reliability of the vessel

Tires: (MEC personnel called them Tracks)

The application used by MEC to install the tires directly to the vessel by shrink fitting the tire directly to the shell has created several catastrophic issues:

Tires that have gone beyond their useful life are impossible to replace in the same manner in which they were originally installed.
Inconsistent wear to the tire is created when the shell does not remain round. This condition creates radial and axial misalignment of the tire.
Application of grease or petroleum lubricants to the tires and trunnions have created pock marks, pitting and ultimately failure of the tires and trunnions.
Resurfacing tires and trunnions will not correct misalignment issues with the tire. All you are doing is removing metal and decreasing structural integrity of the vessel.

RSC has a new design for the tire and mounting system to correct all of these issues

Drive System:

In the effort to save money, MEC used segmented tooth sections attached independently to the dryer along with undersized drive components:

Chain drives are notorious for creating “noise” throughout the vessel. The noise vibration transmits to the surface of the tires and in turn, to the trunnions. This condition causes wear to the face of the tires and trunnions making maintenance of the vessel more difficult. Resurfacing is needed more often to offset the inherent issues caused by the segmented tooth design. The MEC design creates excessive noise in the drive components of the vessel.
Normally MEC drive components tend to be undersized for the vessel. Motors, reducers, chain size and sprockets have all been redesigned to rotate the vessel with the least amount of “noise” that can be produced using a chain drive.

Trunnions & Trunnion Bases:

Poor design of the trunnion assemblies and the bases continue to create alignment issues:

Trunnions are a very simple component when engineered correctly. Unfortunately, MEC trunnions were not manufactured to industry standards. Broken shafts, inconsistent metallurgy and poor installation are just some of the challenges with MEC equipment.
Bearing surfaces on trunnion bases should be flat and when installed should be installed with deep set epoxy machine grout. Most MEC installations don’t even come close to the specifications required to meet industry standards.
Proper alignment of the bases along with shimming and correcting slope issues must be performed when the vessel is installed. Many of the vessels we have repaired started with improperly installed bases and trunnions.