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-   -   6V92 PWM fan upgrade (https://www.wanderlodgeownersgroup.com/forums/showthread.php?t=35206)

badandy 11-07-2019 01:43 PM

6V92 PWM fan upgrade
I guess I'll drop this stuff in here instead of my build thread? Or maybe it should go there? This info might be easier to find here if people actually want to do this, which they should :)

The S60 coaches (LX, LXI?) use a variable-speed hydraulic fan, the old PT is just on and off. The fan motors use the same SAE mount, so it's a bolt-on deal for the fan. The control used for the S60 fan is a PWM electrically-controlled pilot valve thing that controls the speed valve on the fan motor, so you can't have one without the other. I will also be installing a new hydraulic reservoir and at least R&Ring the hyd pump, possibly replacing it with new, and going to a modern plastic fan blade.

Why? I can control the speed of the fan to maintain the set temperature, so when I hit the hills and the fan comes on I don't lose a bunch of speed. It might be more efficient overall, but I doubt by any measurable amount. It's simpler, plumbing-wise. It also doesn't need a high pressure filter, so I'm tossing that out. And I'm a geek, so deal with it! :p

badandy 11-07-2019 01:59 PM

I grabbed some fan data from ACS cooling's website. They have test data for all of their fans, and it's quite revealing! The 392200-32 fan uses between 35 and 50 HP depending on airflow restriction through the radiator. The 440200-32 fan is the same size, but flows more and uses less HP, needs 100 rpm higher speed, so I might go with that one. Interesting stuff.

Randy Dupree 11-07-2019 02:08 PM

The 97-2003 WBs and LXIs use the PWM.
The LX's use the wax control valve.
I think the 450s use the PWM but i think its different from the Series 60 PWM,not really sure.I don't think the 450 guys know either.

badandy 11-07-2019 03:48 PM

Got it, I didn't know when the wax valve stuff was.

Fujimo 11-07-2019 05:18 PM

95 and 96 use wax valve on series 60.,,,42 wide body.

badandy 11-07-2019 11:30 PM

1 Attachment(s)

Here's the old and new fan motors. The beefiness of the new one is quite obvious :) It's only an inch longer and has the same output shaft and mounting holes. It has a really nice shaft seal retained by a e-clip, me likely. And it has smaller hydraulic ports on it, so a little easier to manage the lines.

The cast iron chunk on the side of the new one is the speed (pressure) control that is operated by the wax valve or the PWM valve in my case. If that speed control fails I believe the fan goes to max speed by default, but I have to test that. All I have to give the PWM control is +12/gnd and a PWM signal, varying the duty cycle. I have a little controller with a temp sensor that will take the place of the old fan switch in the thermostat housing. I can set the desired temperature and it will vary the fan speed according to the cooling demands. I can also override it remotely and I will have a readout on the dash up front to tell me the % of the fan speed it's running. Once I get it running I would like to test a few airflow tweaks to see if I can get the fan duty cycle down at all. The mud flaps all across under the engine might be useful?

Oh and thanks to Randy for hooking me up!

Randy Dupree 11-07-2019 11:33 PM

I'm in!
This is interesting,keep the info and pics coming.

Randy Dupree 11-08-2019 09:10 AM

So we can change the cast iron controller and slow down or speed up the fan,if we think thats required?
How about the fan speed itself,if you speed up the stock fan will it stall and not pull air at all?

badandy 11-08-2019 10:25 AM

The max fan speed is set mechanically on the fan motor's valve, they call it the trim. You take the little cap off the side of the motor's valve and change the shims on the spring in there to change the max pressure. Once you do that you've changed the range of pressure you can run, and thus the top RPM. In my case I have a 32" fan, which is smaller than the one it is probably set up for, so I will have to go through this. With PWM control it will run the fan at the exact same speed to maintain the set temp even after you increase this, but the ceiling is higher. I have to get into the datasheet I found for that Danfoss motor. I think top RPM was 2500 continuous and pressure was 3000psi? I can't remember exactly, but there was some room.

The fan blades ACS has datasheets for are all tested in increments to 3000 rpm, most recommended about 2000 rpm. These do not stall out at 3000. I don't know what the factory fan blades would do, but I wouldn't spin the old PT's aluminum one 3000 rpm.

badandy 11-08-2019 11:11 AM

The fan motor is 44 cc/rev
Peak pressure is 3915 psi
Rated pressure is 3625 psi
Max RPM is 2300

This motor is set to 190bar according to the stamped plug, so that's 2755 psi. The bus this came from would have run 1800 RPM, I believe.

Therefore you have 500 more rpm if you have the pump volume to do it on your fancy modern coaches.

I looked up some 38" ACS fans and they test them to run up to 2400rpm. I think the S60s use a 38" fan?

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