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Hydraulic Fan Blades and Motor

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So I was under the coach the other day looking around and getting acquainted with things, making sure the flow valve was in the on position on my coolant filter, taking pictures of filters, transmission tag and the hydraulic fan motor tag. I rotated the fan blades to inspect them and noticed they appeared to be    variable pitch blades. Do these blades have the ability to change pitch like a some people driven aircraft? If so I guess they have some thermostatic control that changes the pitch when the demand calls for more air? I could be wrong and maybe they are just individually replaceable. 


Edited by tmw188
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The pitch can be changed but this is setup by the manufacturer. 

There was a good post on IRV2, one of the members had to completely rebuild his cooling system and provided a detailed writeup with videos, part numbers, and how he did the job.  One of the best writeups I've seen.  He did note that his fan originally was running in the wrong direction, I believe his was pushing out instead of in.  Here is a link to just the write up he did on the fan.  He had a very detailed writeup on the whole cooling system  https://www.irv2.com/forums/f115/97-monaco-dynasty-cooling-fan-507040.html

  Here's the parts page that I have on my fan cooling system.  It does list the vendor part number for the fan blade. 

1 Engine Fan Cooling.pdf

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I would assume there are detents to make sure the blades were all set at the same pitch, but I've never had mine apart.  If you do a search for the vendor part number of the fan blade you can find a company that makes it with documents on how to set it up.  http://www.multi-wing.com/en/products/multi-wing-fan-series/


I now on large ventilation fans (200-400 hp) they are pitch settings with detents so you can change the pitch.   Makes a big difference on energy demand, amperage on the motors will change with the slightest change in pitch. 

Edited by jacwjames
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18 minutes ago, milly59 said:

if it pulls in does not pull air when at speed as there is a vaccum pulling the other way.when running..had a monaco 43 and ambassador 40 both pushing air out w back radiator.

It’s a side radiator with hydraulic driven fan motor. 

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I had to replace the blades on our 2005 Exec (Detroit, side radiator) several years ago. If I recall correctly, the blades have a fixed pitch that is molded into the hub ends. It’s a 2-part hub that comes apart to fit the blades into each socket.

Ours needed to be replaced because the welds failed on the “X” frame that Monaco fabricated to hold the fan motor in place. It was only held on in one corner. I was able to salvage enough blade debris to get the part number to order from MultiWing. I think the direction, pitch and length were coded into the part numbers. I think ours took 12 blades.

I usually caution folks with similar setups to check their fan motor bracket for cracks at least annually. 

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