Hydraulic Fans and Power Steering Systems

Topic: Hydraulic Fans and Power Steering Systems (Read 2693 times) previous topic - next topic

Hydraulic Fans and Power Steering Systems

July 14, 2020, 09:26:18 am

Good Morning All,
I have been working on making my 2 hydraulic radiator fans run at top speed. Foretravel Specs:
Pump Output 1600PSI @ 2750RPM
Fan Speed High 2930RPM @ 2750RPM 2250RPM
Fan Speed Low 1900RPM @ 2750RPM 1600RPM

For several years I have know that the fans and the power steering were tied together some way. I have two(2) fluid tanks, up until a few days ago I thought I had only one hydraulic pump(pump w/belt). I now know that there is a pump driven by the CAT 3116 Air Compressor on the back side of the compressor. I have been told lately that the systems are tied together as a backup. If the power steering pump goes out the system will still/rob from the fan system to maintain steering. I was told that the "star value"/priority value does this by giving that power steering system over the fans.

Now that I have found the second pump, can a bad/week/something wrong pump make may fans run slow?? The "star value"/priority value when closed(low PS priority setting) does not effect PS. At idle I have good PS.

Pat,

Re: Hydraulic Fans and Power Steering Systems

Reply #1 – July 14, 2020, 09:48:41 am

Quote from: pthurman48 – July 14, 2020, 09:26:18 am

I have been told lately that the systems are tied together as a backup. If the power steering pump goes out the system will still/rob from the fan system to maintain steering.

News to me! Never heard anything about this from reading on the Forum.

Our coach has the two separate hydraulic reservoirs, and two separate hydraulic pumps. The cooling fan pump is belt driven - the power steering pump is driven off the rear end of the engine air compressor. I have always "assumed" that the two systems are completely isolated from each other. I have never found any hydraulic line connecting the two systems.

Best I have been able to determine, my cooling fans do not have a "2 speed" control valve. If it exists, I have not been able to find it. My cooling fan speed seems to be totally engine RPM (pump RPM) dependent - IE as the engine RPM goes up the fan speed goes up.

I rebuilt our cooling fan pump 5 years ago. I bought a cheap non-contact tachometer at Harbor Freight to check the fan speed before and after the rebuild. I only checked the speed at idle - don't remember what the RPM was.

https://www.harborfreight.com/digital-photo-sensor-tachometer-66632.html

Vickers V10 Hydraulic Pump Rebuild

Re: Hydraulic Fans and Power Steering Systems

Reply #2 – July 14, 2020, 03:08:19 pm

Yours may be different but my hydraulic fans run on high speed by way of a solenoid bolted to the chassis, drivers side basically across from the coolant filter (Cummins). If I remove the top nut and take the solenoid off it defaults the fans to high. I have 2 pumps and nothing is back up of another. In addition, my fans don't kick to high until 203'ish degrees.

Re: Hydraulic Fans and Power Steering Systems

Reply #3 – July 14, 2020, 03:52:43 pm

My system is the same. My system has a small aluminum block on the opposite side(passenger side) that has a nut and allen head wrench nut. I was told by FT that this "star valve" controlled the amount of fluid that went to the power steering. They told me to adjust it so that at idle I had a little power steering help. They also said that it controlled the max speed of the cooling fans. I saw them turn it and say that "we should be able to to make them sing". This happened when I had them work on the slow speed of the fans. They replaced the hydraulic pump and the star valve(4 yrs ago) and then told me after $2500 that the 2 fan motors were at fault and I should replace them. I bought them from FT for $2400 and put them on myself. I still have the old fan motors. I also still have 2 fans that are still running slow by about 6-7 hundred RPM. That makes my little kitty CAT run hot real easy.

I got on this problem again due to the fact that my CAT 3116 Air Compressor has gotten week. I am replacing it and I noticed a pump bolted onto the rear of the air compressor. I did not know that I had 2 hydraulic pumps on my MH. I thought I had only the belt driven pump and it did both PS and cooling fans. I just want my fans to run Fan Speed High 2930RPM @ 2750RPM and mine is still at 2250RPM.

Re: Hydraulic Fans and Power Steering Systems

Reply #4 – July 14, 2020, 04:19:24 pm

Quote from: Twig – July 14, 2020, 03:08:19 pm

...my hydraulic fans run on high speed by way of a solenoid bolted to the chassis, drivers side basically across from the coolant filter (Cummins).

I don't suppose you have a photo of that solenoid? I don't think there is anything like that on my coach.

Re: Hydraulic Fans and Power Steering Systems

Reply #5 – July 14, 2020, 08:03:45 pm

Quote from: Chuck & Jeannie – July 14, 2020, 04:19:24 pm

I don't suppose you have a photo of that solenoid? I don't think there is anything like that on my coach.

Some have it, some don't. Foretravel. Go figger, eh?

Re: Hydraulic Fans and Power Steering Systems

Reply #6 – July 14, 2020, 08:28:15 pm

Quote from: Twig – July 14, 2020, 08:03:45 pm

Some have it, some don't. Foretravel. Go figger, eh?

I have the same solenoid, the ground connection from the coil goes to a temperature switch mounted on the side of the block below the turbo. Contacts are N.C. until temp reaches 190* then it opens and drops out the coil to the solenoid and with the coil de-energized high flow is directed to the fan motors.

Re: Hydraulic Fans and Power Steering Systems

Reply #7 – July 14, 2020, 08:31:10 pm

Twig,

Thanx for the photo confirmation. Nope, I don't have one of those solenoids anywhere in the engine compartment. I woulda seen it.

We have never had a overheating problem, so whatever controls the speed of my fans seems to do the job.

Perhaps, because the '94 and '95 GVs are closer (mechanically) to the Unicoach, they got a upgrade to the cooling fan system.

Re: Hydraulic Fans and Power Steering Systems

Reply #8 – July 15, 2020, 10:29:12 am

Mine had the same solenoid controlled by temp sensor in water jacket near thermostat. The thought was to increase diesel mileage. When my temp sensor failed and I overheated my engine, I removed the ground at the solenoid and ran it to the dash on a spare wire, where I installed a rocker switch to control the speed of the fans. At 1500 rpm I can switch the fans from low to high speed and see the decrease in rpm by 30-50 rpm. That shows that the high speed fans do take some power to run and would decrease diesel mileage. In cool weather or early morning I can run on low speed fans. My problem is that my fan speed is about 600-700 rpm slow on both low and high speed.

Just FYI
I found my OEM PS pump(new) for $389 on internet, FT wanted $692, found a rebuild shop for $325
Vickers Pump V10F1S5T38C4H20
be here in 3 days UPS.

Pat,

Re: Hydraulic Fans and Power Steering Systems

Reply #9 – July 15, 2020, 10:43:55 am

Quote from: pthurman48 – July 15, 2020, 10:29:12 am

I found my OEM PS pump(new) for $389 on internet, FT wanted $692, found a rebuild shop for $325
Vickers Pump V10F1S5T38C4H20

Good find!

For other members who might have this same V10 pump, if you have pump problems and are not lucky enough to find a new one, there is hope! It is possible to rebuild the pump, and the process is fairly simple. The trick is finding the parts. Details linked below:

Vickers V10 Hydraulic Pump Rebuild

Re: Hydraulic Fans and Power Steering Systems

Reply #10 – July 25, 2020, 10:33:16 am

Update:
I have a Marine Corp.Trained Grand Son that works for John Deere in Beaumont, TX. He is a job site diesel/hydraulic/what ever it takes mechanic. I asked him

I really don't under stand the two systems. Is it common to have two pumps with 2 tanks? how to they keep the right amount of fluid in the tanks? Is that star-valve where the two systems are tied together?

He responded

On our equipment there is a hydraulic pump and a fan pump. The fan pump runs the fan under all conditions unless the hydraulic pump fails then the priority valve shifts over and the fan pump will run steering and/or brakes. It is strictly a safety thing. They would rather you were able to steer and stop in a failure situation. On deere they use the same tank but the priority valve is supposed to shift and separate the systems

I still need more help to understand, 2 pumps, 2 tanks and how they keep the fluid level in each system correct.

Pat,

Re: Hydraulic Fans and Power Steering Systems

Reply #11 – August 28, 2021, 11:51:40 am

Update for this old problem,

I have now after 4 days made a drawing of the hose nightmare that FT created. I now know more about the system also.

1. Star Controller is nothing more that a safety valve for over pressure.
2. The Hi/Low solenoid valve is a on/off valve nothing more.
3. The fans run as fast as the pump sends fluid.
4. My original pump was a John S. Barns(w29a-18000118) not available anywhere.
5. My replacement pump is a Sauer/Danfoss(80002642).

FT replaced the pump and Star Controller, I replaced both fan motors with new ones and the Hi/Low Solenoid Valve. With all new components my fans still run about 700rpm slow on both hi and low speeds. Otherwise the system works fine. I added a switch on the dash to control the Hi/Low Solenoid Valve. I have high speed fans on demand.

Engine RPM         Fan 1(Front)   Fan 2(Rear)
low/hi low/hi
700            483/679      470/666
1300            795/1093      785/1087
2750            1620/2250   1600/2202

Foretravel Specs:
Pump Output 1600PSI @ 2750RPM
Fan Speed High 2930RPM @ 2750RPM
Fan Speed Low 1900RPM @ 2750RPM

My next thought is: Is the pump turning the correct rpm for my motor(cat 3116)?
My crank pulley and pump pulley are the same 6". That makes my pump run from 700rpm up to 2650rpm.
What is the size of your pulleys and are they different size?

Re: Hydraulic Fans and Power Steering Systems

Reply #12 – August 29, 2021, 01:05:14 am

I don't know anything about the Hydraulic Cooling Fans but I have this from David Pedigo

Re: Hydraulic Fans and Power Steering Systems

Reply #13 – August 29, 2021, 08:27:13 am

Interesting how many variations of these hydraulic systems are found in Foretravel coaches. My '93 model U280 has two totally separate hydraulic systems. There is no connection of any kind between them. The gear driven pump on the side of the engine drives the power steering system. The belt driven pump mounted below the alternator drives the cooling fans.

My cooling fan hydraulic system is simpler than Pat's. Looking at his diagram (above) my system does not have the high/low solenoid valve or the star control relief valve. My fans turn any time the engine is running. Fan speed is determined solely by engine RPM. As engine speed increases fan speed increases. Seems to work fine - we have never had any overheating problem (radiator is still original). Knock wood.

Re: Hydraulic Fans and Power Steering Systems

Reply #14 – August 29, 2021, 10:38:08 am

Good Morning,
Chuck, my system is like yours. My power steering pump is shaft driven by the air compressor that it is bolts to. My cooling fan pump is belt driven from the CAT 3116 crank. The pulleys on crank and pump are 6", that means the pump runs at engine rpm(700-2650). You will have a pressure relief valve some where. My brother had a 93 U-240 and it did not have a hi/low valve. It had one big fan. My fans run about 700 rpm slow, I have had this problem for years. I can keep the temps under 210 most of the time, but going thru Albuquerque, NM in August is a problem.

Re: Hydraulic Fans and Power Steering Systems

Reply #15 – August 29, 2021, 11:28:00 am

Chuck,

Our 1993 U300 with the Detroit also has a direct drive PS pump with separate reservoir with the pump located at the opposite end of the engine. The radiator fans/pump are belt driven off the crank pulley.

Pierce

Re: Hydraulic Fans and Power Steering Systems

Reply #16 – August 29, 2021, 12:17:10 pm

Quote from: pthurman48 – August 29, 2021, 10:38:08 am

The pulleys on crank and pump are 6", that means the pump runs at engine rpm(700-2650). You will have a pressure relief valve some where.

In Reply #9 up above (posted a year ago) I have links to the tech sheets on the V10 pump used in my coach. I think they mentioned something about an internal pressure relief valve in the pump.

I'll have to look at the size of my crank pulley versus the drive pulley on the pump - see if they are the same size. Interesting.

Even if the pulleys on crank and pump are the same diameter, does that necessarily mean the fans run at the same RPM as the engine? There may be some kind of variable ratio between the pump speed and the fan motor speed. For instance, 100 revolutions of the pump may only produce 50 revolutions of the fan blades. Something like that... Just wonderin'.

How do you measure the RPM of your fans? When I rebuilt my pump, I bought a tachometer at Harbor Freight to check the fan speed before and after my rebuild. It worked pretty good. I only measured the speed at idle. I wrote it down somewhere...can't find it now. At the time it did not occur to me to measure at higher RPMs. Might put that on my list of future "projects".

https://www.harborfreight.com/digital-photo-sensor-tachometer-66632.html

Re: Hydraulic Fans and Power Steering Systems

Reply #17 – August 29, 2021, 12:20:35 pm

Quote from: Twig – July 14, 2020, 08:03:45 pm

Some have it, some don't. Foretravel. Go figger, eh?

Since I work on a lot of different coaches- Monaco was built either in Indiana or Oregon- using the same prints but turning out different coaches.

Re: Hydraulic Fans and Power Steering Systems

Reply #18 – August 29, 2021, 02:48:40 pm

Chuck,
In response to the question about how to check fan speed. FT told me to check at WOT. I use a hand held laser tach. This what I get and the FT specs.

Engine RPM Fan 1(Front) Fan 2(Rear)
low/hi low/hi
700 483/679 470/666
1300 795/1093 785/1087
2750 1620/2250 1600/2202

Foretravel Specs:
Pump Output 1600PSI @ 2750RPM
Fan Speed High 2930RPM @ 2750RPM
Fan Speed Low 1900RPM @ 2750RPM

Pat,

Re: Hydraulic Fans and Power Steering Systems

Reply #19 – September 09, 2021, 10:48:30 am

Quote from: pthurman48 – August 29, 2021, 10:38:08 am

Good Morning,
Chuck, my system is like yours. My cooling fan pump is belt driven from the CAT 3116 crank. The pulleys on crank and pump are 6", that means the pump runs at engine rpm(700-2650).

I just remembered this morning that I wanted to check the diameter of the pulleys on my coach, to see if they are the same as yours. Turns out my hydraulic fan pump pulley is 5" and the crank pulley is 6.25" so my pump is running faster than engine RPM (25% overdriven ?). Interesting tidbit of knowledge to file away for future reference.

Re: Hydraulic Fans and Power Steering Systems

Reply #20 – September 09, 2021, 11:37:17 am

Pat, to this novice it seems the pump is the issue.
Any way to check the pressure?
Joe

Re: Hydraulic Fans and Power Steering Systems

Reply #21 – September 09, 2021, 12:19:11 pm

Be sure that nothing in the plumbing system reduces the line size to less than the pump output size anywhere all the way through and
back to the pump.
For a given pressure, flow will be effected by line size. That would effect fan motor speed.

Re: Hydraulic Fans and Power Steering Systems

Reply #22 – September 10, 2021, 08:25:44 am

Chuck, Joe, and John, Good Morning,
Thanks for the checking of the pulleys on your system.
Since the last writing, I changed the filters in the oil tank. There is 3 of them, round medal outside with paper inside. The change made no difference. My grandson sent me a pic of a school bus pressure and flow info chart(included in the post). It looks like the engine and pump on it is running at engine speed.

Joe, I have been waiting for two(2) weeks on Rodney Blackman from FT to help me with pressure and flow info on my system and as of now I have heard nothing, I also have checked back with FT about it and I have heard nothing. The pump maker(sauer/Danfoss) will not give any info due to the fact that they make the pump for FT and tell you to contact the OEM(FT).

John, I agree I think the pump is running to slow. When I first had the problem, FT changed the old pump(John S. Barnes) to the new one(Sauer/Danfoss), also changed the star controller and then told me the problem is/was with the fan motors. I replaced both of them with new ones. I have also changed the HI/Low Solenoid Value, nothing has had any effect on fan speed.

Chuck, Thanks for checking those pulleys. I don't know and would like to know how fast can you turn the pump without damage to anything in the system?

Thanks for all the help, I sure need it, I have been fighting this for a while now.

Pat,

Re: Hydraulic Fans and Power Steering Systems

Reply #23 – September 10, 2021, 09:36:14 am

Quote from: pthurman48 – September 10, 2021, 08:25:44 am

Chuck, Thanks for checking those pulleys. I don't know and would like to know how fast can you turn the pump without damage to anything in the system?

I just Googled and found the document linked below. It specifies the max RPM numbers for the type pump fitted to my coach. My hydraulic pump is model number V10F 1S5T 1C10J 20. Looking on page 7 of the document, I see that my pump has a "ring size" of 5 (5 USgpm). At the bottom of the page, chart says a V10 pump with ring size 5 has a maximum rpm of 3200.

My C8.3 engine has governed HP rating of 285 @ 2400 RPM. Governor break RPM = 2450, and high idle (MAXIMUM ALLOWABLE RPM) limit = 2760. I have never seen over 2400 RPM in "normal" driving, including during full throttle upshifts.

Since my pump is 25% overdriven, at 2400 engine RPM the pump would be turning 3000 RPM (2400 X 1.25). This is near the max pump RPM with a little safety margin for transitory over-speeds, like when I'm using our exhaust brake on steep grades. I try to avoid exceeding 2500 RPM when using the exhaust brake.

Don't know if this answers your question. I assume the fan motors would also have some maximum RPM limitation.

https://www.appliedfluidpower.com/media/wysiwyg/PDFs/V10.pdf

Re: Hydraulic Fans and Power Steering Systems

Reply #24 – September 10, 2021, 02:26:16 pm

Thanks Chuck, I also have a Vickers Power Steering pump(v101f1s5t38c4h20r) running on the back side of my air compressor, but my hydraulic FAN pump running off a belt is a replacement for my original John S. Barns pump and it is a Sauer/Danfoss.

Pat,

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