CBW Preventive Maintenance

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The most important item on any PM should be Safety. This is especially true with CBW’s(Continuous Batch Washers or Tunnel Washer). Chemicals, Scalding water, slippery surfaces and rotating equipment to name only a few of the Hazards associated with a PM to a Tunnel Washer. This review will be on a Lavatec Tunnel but the procedures are essentially the same for most of the Tunnel Washers in use today.


  1. When to PM?

Most Tunnel Manufactures list the Normal week of operation as 40 to 50 hours per week. The Weekly, Monthly, Semi-annual and Annual PM’s listed in the Equipment Technical Manual are based on this, 40 to 50 hours per week of operation. If the Tunnel Washer is in operation 16 to 24 hours per day then the Monthly maintenance becomes a PM to accomplish on a Weekly basis as an example.

  1. What to Do during a PM?
  1. Prior to shutting the Tunnel Washer observe the operation of the Tunnel. This is when I check the rotation. When the drive motors engage you wish to have the drum already turning in that direction due to its momentum. Drive motors engaging to late (when the drum starts to turn the opposite direction) causes severe wear to the belts, drive wheels, gearmotors and such. On chain driven Tunnels (Milnor – Sinking, ECT) this will also damage mounts, chain and even the drum. Do this with a full load in the tunnel. Make any adjustments to the rotation Time delay relays, Programming depending on the Tunnel and age.
  2. Check the amperage draw on each of the motors at the overloads. You need to see an equal amount of amp draw from each motor. Too much of a difference signals a problem such as loose belts (causes the other motors with good belts to carry too much load) motors engaging too late, Gearmotor problems and such. Investigate any change from the last PM.
  3. Make sure the cabinet cooling fans are working.
  4. While it is running check the water flow. Lavatec Tunnels are crossflow Tunnels and too much or too little water not only can cause cleaning the linen difficult this will also cause Plugs, Roping and Jams. Watch the flushing water leave the trough on the chute. Is it uniform or seems like more water is coming from one area that the other? I use a long wood saw zaw blade in the narrow opening to clean out the debris that can clog the opening. This can really increase the water flow into the chute and be more effective in pushing the load into compartment One. Check the Weir boxes to ensure good water flow and the water flow gauges for correct flow. Check that all sample hoses and level switch hoses are clear. Doing this will all but eliminate plug tunnels. As a side note check the Flushing pumps on your Lavatec Tunnel. Everyone I have worked on had the two pumps tied together via a TEE to the Chute. I am a pump guy at heart and this is just wrong. They were fighting each other. I piped them to each side by themselves and now have a lot fewer problems with those pump seals and a lot better flow (Push) of water down the Chute. Helped to push those bulky loads into the opening. Check the Water tanks and drain valves. Check the water flow going into the last compartment. If the Valve is leaking by then too much water will be in the compartment and splash out and possible to fault the press or have linen float towards the front and a possible plug. If the load does not flow smoothly into the press programming more water into this compartment can help.
  5. Test all the E – Stops.
  6. After shutting down the Tunnel and Locking it out check the Drive wheels, Belts, Thrust bearings under the front drive ring and the axial movement limit switches. Switches are on the Left side of the Tunnel. (Note: Left, right, forward and back is referenced by the flow of linen. Face the flow as the reference. The components are wired this way.) If I need to change out one set of belts I change them all. Prevents one gearmotor momentarily having the full load or slipping. Grease the Drive wheel bearings. Some Tech manuals say this does not need to be done but you need to do it. I have removed these bearings from tunnels and they were full of rust. You only need to put in ONE stroke of grease if there is any sign of grease coming out of the bearing. Do this last to allow the grease to cool. (Note: Always push grease in SLOWELY! There are times you can blow out seals and cause damage. A Grease Gun can develop 6000 Psi of pressure. A count of 10 to stroke in one stroke of grease is a good habit. On Milnor bearings I double that time due to me changing a LOT of seals damaged from overpressure.)
  7. Clean out the water tanks, Lint separator and weir boxes as needed. If you do not have drains on the compartments then open the bottom where bleach enters. Any build up of debris, sand or such can absorb the bleach and eat away at the bottom of that compartment. Once a month I remove the fittings where chemicals enter the compartments and flush them to prevent corrosion. I have had to weld in some of these before. Ensure the Brushes, Drive chain, sprockets and bushings are good on the Lint Seperator.
  8. Blow out the control cabinet and all the motors. Change out the filter media. Blow out the Drive wheels as well.
  9. Note any seals that are leaking that will need to be changed.
  10. Clean the Chute Photocell. Place a 6 ft ladder into the chute to help getting to the sensor.
  11. Tech Manual states to change out Gearmotor oil every 10,000 Hours. 24/7 = 8736 hours per year. I do this once a year and I use a higher viscosity gear oil as well. The gear box is next to a very hot and humid environment. I also check the level monthly. I had a trainee not check these and when I asked him why he stated there was no oil on the platform thus no leak. I crawled under there with him and checked them. One had almost no oil. The oil had leaked into the MOTOR. He now checks them every month!!
  12. Check the Flags and 5 rotatation Proxes for damage and corrosion.
  13. Drain Air filter and fill lubricator.
  14. Check drain air cylinders. These will be in the Water Tanks and Weir Boxes.
  15. Check that the rinse water pneumatic does not leak by. (Note: The Brass valve body on the valve is rated at 150 Psi @ 72 degrees. If you have rinse water at 140 degrees or above these will leak by. I change out all of mine to an Asco Stainless steel Valve. Have not changed one in 10 years!! I do this to All my HOT water solenoid or inlet valves for all my washers. Use “Steam” valves for the hot water and you will actually spend a lot less.
  16. Install all the covers, Remove the Locks and Test.

Preventive and Predictive Maintenance are the life blood of any mechanical device. The “ounce of Prevention” should be the Maintenance Mantra as it can never be more true. Please conduct all PMs with Safety in mind to yourselves and to the people around the Tunnel. Some tunnels and the laundries they are in will add more to this PM but it covers most of what to look for. I covered some things done only on monthly or yearly PMs to illustrate what to investigate their equipment during a PM.

Mark McLeod – AKA TUNNELTECH

  • matt s said,

    This is a very helpful article thanks for your experience and advice.