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GEAR BOX TO FAN CLUTCH BELT TENSIONER
This has been discussed before, but I think it is important enough to be repeated, but also to encourage everyone to make this issue not only a part of the pre-trip inspection, but a vital part of the chassis maintenance.
The background is simple. On Series 60 coaches the flat belt that runs between the fan clutch and gear box is kept under the correct tension with a roller bearing on the arm that presses the belt tight when the belt air bags are inflated. That arm pivots as the miniature air bag is inflated and the roller tightens the belt and provides a surface it rolls over.
It is a simple system and is generally reliable.
But its reliability is compromised because of 2 potential reasons, The first is the grease fitting at the pivot point on the arm is easily missed and since that arm is constantly bouncing up and down when the belt is under tension dry bushings are going to wear prematurely. Making it worse, a lot of owners only do an annual service. Often that means even if the grease fitting is lubricated, it is not happening often enough and the inadequate lubing is going to contribute to dry bushings.
The reason this adjusting arm needs to be inspected, and maintained is if the bushings wear, the support bearing the belt relies on for tightening the belt will not be parallel to the belt and because the roller bearing is tipped with respect to the belt, it has a tendency to force the belt to travel sideways. By applying a sideways force to the belt instead of just a flat surface for the belt to glide over the belt is being pushed sideways on the fan clutch pullet and the gear box drive pulley. Constant sideways force on the belt can shred the side of the belt, or cause it to “walk” sideways on the pulleys.
That could damage the belt, cause the belt to come off the pulleys, shred the belt, or even cause the belt to wrap around the gear box puley shaft and potentially damaging the gear box pulley seal.
So rule one is to always insure the arm pivot point grease fitting gets a shot of grease, every 6200 miles if possible. Rule two is to include the arm in the pre-trip inspection. To do this relax the belts by turning off the belt tensioner knob, and then see if the arm can be moved sideways. It should not. It should move up and down, but never have a sideways wobble.
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20 Replies
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Thanks for the reminder, I will check mine today.
Jerry
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Jon,
Thanks for all the tips you give…could you please upload a picture on where the grease point is? Also what type of grease would i use?
Thanks
David Thomas
1998 Featherlight XL
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I can’t get a photo of the grease fitting right away, but I can describe its location.
On Series 60 coaches there is a flat belt running from the gear box to the fan clutch. That belt is kept tight by a roller that is mounted on an arm that pivots upward to put tension on the belt.
The pivot point for the arm on which the big roller (2 to 3″ in diameter and about 1/2″ wider than the belt) is mounted is down low at the lower end of the arm. Look straight into that area just to the right of the radiator and you will see at the bottom end of the arm holding the roller is a grease fitting. If you aren’t looking for it or do not know it is there you will never see it.
It is shown on the diagram for grease fittings, but to actually see it you need to know it is there, you need a good flashlight, and maybe even a rag to wipe away old hardened grease that hides the grease fitting shape.
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That zerk fitting almost never gets any attention. Good post from Jon, greasing that pivot point will save the day.
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Yes Jon thx for the post – I need to ck that also.
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Jon I found fitting, greased it found follower spun free, too free no grease so I ordered a new bearing 20mm x 52mm double rollers 22.2mm wide
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Is this it?
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That’s it
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Thanks Roy.
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Jon:
Just check Eng compartment and sure enough there it was hiding behind the fan gear box. Definitely had not been greased in a long time although is was still OK.
Its these little things in the post that make a big difference.
Thanks againChuck
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Do all S60 have the grease fitting , I dont see one on mine. my dad checked his coach, he doesnt see one either.
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Look on the diagram for lubricating for your coach. If it has one it will be shown.
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Hello,
What model of grease gun and grease should I use for this?
Thanks
David Thomas
1998 Featherlight XL
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Any type of grease and any kind of gun that will push grease into the fitting will work.
The more appropriate question is if whoever is taking care of your coach maintenance doesn’t grease that fitting, why would you continue to use them?
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Jon,
Frankly I don’t know if the fittings are being done or not. Prevost or Marathon in Dallas do my annual inspections and Level 3 services annually. At Prevost I am not allowed to talk to the technicians and Marathon I don’t always know what they do, as I am taking my naps.
What I do know is that I only service and inspect my coach annually and my understanding from this tread is greasing needs to be completed every 6 months, so I am trying to understand what points on the coach need greasing.
Thanks
David Thomas
1998 Featherlight XL
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