Air Cylinder/Top Brush Jumping

[Burky]

Hello. I have a soft touch car wash that has the top roller/brush connected via belts to an air cylinder. When the air cylinder retracts the brush goes up and when it extends the brush goes down gravity. Speed is controlled via flow valves and direction is controlled via Mac valves. The one side of the cylinder is vented to atmosphere.(tubing to dry eq. Room)

I had trouble with the brush starting to “jump” so I replaced all the bearings on the rollers of the top brush track and purchased an air dryer at the suggestion of the local cylinder shop. None of this solved the problem so I purchased a new air cylinder (ships from Italy)

This also has not solved the problem. I replaced the Mac valves as well even though I knew they were functioning properly and the cylinder still behaves in the same method, even when using an alternate air supply.

Brush “jumps” in both directions.

I’m thinking of adding an oiler to the cylinder, but wanted to see what the consensus is on this forum.

 

[Ryko CS]

You didn't mention what model machine you are working on, but when the top brush "jumps", is an output coming on from the PLC of the machine to actuate the MAC valve? If so, then the program is likely controlling that "jump". If the TB is controlled via an air cylinder via belts, this sounds like a common layout of a 3 brush model machine, and many of those are controlled through am amp sensor input to the PLC.

In those types of machines, they monitor the amp sensors are often setup with steps where once it reaches a certain threshold, the PLC will output that the brush needs to raise as it has too much "crush" (or pressing too hard) on the vehicle surface. They usually have a range where it is considered "normal" crush, and also not enough crush which the PLC would then lower the brush for more pressure. If those ranges are setup too close together, it will give the appearance of the brush "jumping" as you describe because it's just constantly trying to adjust to be within the "normal" range.

I wouldn't usually recommend adding an oiler to the air system for the cylinder as often times that same air source will be used on-board the machine also to foam chemicals. You don't want that oil being sprayed upon the vehicle surface with a foamed detergent or drying agent.

 

[Burky]

Thanks for your reply. It is indeed a Ryko Machine. Yes the Mac valves are controlled via the PLC that is monitoring the amp clamps as you stated and it is a three brush machine.

The brush jumps even when it is not touching the vehicle. I have monitored the outputs of the PLC to the Mac valves as well as the inputs from the four levels of sensitivity on the top brush, and I do not think it is some thing that the PLC is instigating. The brush also jumps when I do a top brush drop from the HMI.
If I add an oiler it would be after the Mac valves right on the cylinder to prevent oil from being applied with chemicals.

I should add that the brush/cylinder jumps, even when I use an air source that is not routed through the Mac valves.

 

[Ryko CS]

I would recommend you reach out to a company called Chroma Service in Italy. Several of their employees came from Ryko Italia and they would be specialists on those machines. Salvatore and his team can be contacted at service@croma-croma.com

 

[Burky]

Thanks so much for the info! I have sent them a email and will let you know what I find. If we find a solution I will be sure to post it back here.
Cheers!

 

[Ryko CS]

I sent you a PM yesterday too.