P/S pump enough umphh ?

[Brian R.]

    I have a 6v92 out of a 1983 MC-9 that I'm putting into my MC-2.  The 6v92 has a power steering pump driven by accessory drive on engine beneath the compressor.  My bus (the MC-2) has no power steering and I don't need it. 
    My question is this:  Can that power steering pump power a hydraulic motor to run the cooling fan on a third radiator that I added to the system long ago (it is powered by electric motor now).
    The only info I can find about the pump is that it is a Vickers and is 1500psi max. (I found info on a 1989 MC-9 pump that runs 4gpm, but I don't know if it is the same pump.)
    Supposing those specs( 1500psi, 4gpm) I don't know if the pump would have enough power to run a Hyd.fan motor at sufficient speed/torque. Researching these motors gets complicated, some are two stage, most all involve running both p/s and hyd. fan, and most are variable speed.
    This being a third radiator with only an 18" fan (with the electric motor turning around 2,500rpm @ 60amp, that I have on a switch and a thermostat) I want to keep it simple, i.e. -no variable speed,etc.  Would probably need an oil cooler for it, maybe.
    Before I start calling hydraulic fan motor salesman/techs and believing them, I thought to run it by you fellows on the forum. I have already visited several hyd. repair outfits but they couldn't contribute much.   Cheers.

[Jim Blackwood]

It'll pump a lot more fluid than your fan motor is going to need but can be made to work if you match the displacement of the motor to the pump. Otherwise you may find the motor is running way faster than you want it to.

You can measure the displacement easily enough with a bucket of fluid and a measuring cup. Turn the shaft a few times and see what comes out. Same for the motor.

Jim

[luvrbus]

Most fan motors like the Sauer or Danfoss require 10 to 15 GPM, and 3300 to 4000 psi for a single stage hydraulic fan motors and you need to add a Wax valve to control the speeds it can get expensive keep your electric fan the Vicker 42 pump is not going to cut it 

[HB of CJ]

Not enough pump?  My old Crown 10 wheeler had a Victors VT42 to work the steering.  Seems the prior owner hung the wrong pump.  We went with a much bigger (more $$$) Victors to let the 16K front axle steering work.  Wow.

I believe a mechanic versed with things making something work my be indicated.

[Utahclaimjumper]

 The Vickers pump on my American Tradition runs the side mounted fan AND the power steering also.. I learned the hard way that the use of ATF with the Vickers will shorten the life of the pump,, mine went 149K before giving up.. When I replaced the pump and cleaned the system I went with AMSOIL Torque Drive for more wear additives..>>>Dan

[luvrbus]

The Vickers pump on my American Tradition runs the side mounted fan AND the power steering also.. I learned the hard way that the use of ATF with the Vickers will shorten the life of the pump,, mine went 149K before giving up.. When I replaced the pump and cleaned the system I went with AMSOIL Torque Drive for more wear additives..>>>Dan

Vickers makes lot of different pumps which one do have a single stage or 2 stage pump

[Jim Blackwood]

If you don't know the pump and the motor displacement you are just pissing in the wind. Any quality hydraulic pump is capable of making well over 5000 psi, pressure is not going to be the issue. Any hydraulic motor that matches that pump displacement is going to be more than capable of tearing the hub right out of the fan if it were held stationary. If the pump and motor are the same displacement the fan will run at the same speed the pump is driven at. Is that the speed you want?

If not, change the displacements accordingly. A motor with twice the displacement will run at half the speed and vice versa.

If you were to put a pressure gage on the high side of one of those hydraulic fan drives I'd be surprised if you saw even a few hundred lbs of pressure when it is running.

Jim

[luvrbus]

I am 800 to to 1200 psi at the fan motor running @ 12gpm a lot depends on the pump being a open center or closed center, vane type or gear type on a system, a hydraulic system requires valving, or you are pissing in the wind, some of the older John Deere construction equipment used a piston type pump that was a nightmare for me

[Brian R.]

Thanks for the input guys. Haven't been able to id the pump other than embossed   "Vickers - vane pump "   and a 7 digit casting number. Also a metal tag affixed to it that says:     " Caution- 1500psi pump- use only on coaches equiped with integral power steering"    (Could find nothing online about the casting number). It was only for power steering so maybe it is only a single stage pump.   
    This pump is on a 6v92 ( only a 270hp TTA) from a 1983 MC-9.  I will start calling UCP,IBP and other parts outfits to try to id.(maybe Luke can find it).   A 1989 MC-9 Maintenance manual mentions that the p/s pump is a 4gpm, chances are it is the same.
    The reason I want to go hydraulic on this third radiator is mildly interesting.  In 1984 when I was installing the 6v71, I removed the squirrel cage fan and installed a 60 amp electric motor with fan for each radiator. (That worked fine despite Tom Luft, who was a great source of info, at MCI relating that MCI  had experimented and given up on electrics,---I do avoid 8,000+ft passes).
     About 10 years ago, in anticipation of someday installing a 6v92(more heat) I installed a 3rd radiator with another 60 amp motor. I never really needed it so never had all 3 running at once.  The issue is this: I am leery of putting so much demand on the 50dn alternator( which is belt driven off the blower drive).   A 120 amp demand from those motors is one thing, a 180 amp demand is another.   A little concerned about the strain on the blower drive also( it has the oldtime fiber disk)
     If I could go with a hyd.fan motor I was thinking to basically run it all the time(its only one third of the cooling system) and bring the electric motors online as needed, which would be when warmed up.  Want to keep it simple but in the end would do whats gotta be done short of breaking the bank.
     If this motor didn't already have a p/s pump I would probably not be entertaining the idea. I would instead be looking into 400 amp alternators but those don't come cheap. I may be pissing into the wind but sometimes that is how you learn your lessons.---Cheers

[Iceni John]

A PS box requires much less fluid flow than a fan motor:  I'm guessing your 4GPM pump is sized for a PS box, but wouldn't be much use for a fan motor.   I have a hydraulic fan in my bus, using a Webster 280KB pump (2.8 cu.inches per rev.) and a Webster M194YC motor (1.94 cu.inches per rev.), and the fan turns at about engine speed, with a maximum of about 1200 PSI at 2100 RPM engine speed.   I installed a Prince RD-1875H pressure relief valve to prevent any pressure spikes over 1500 PSI reaching the motor, but the Danfoss 7WA110-2 solenoid directional control valve also has a pressure relief valve in it, I think.   The Danfoss SDCV diverts half the flow when energized, running the fan at about half speed when the coolant is below 195F.   The fluid now never exceeds 140F, using the original Hayden hydraulic fluid cooler that I've mounted in front of a new transmission fluid remote cooler located in the airstream under the bus (I hate to block airflow to the main radiator where the hydraulic cooler was before).

John

[Utahclaimjumper]

 If your old pump took a hike,, you will have to drain and clean the reservoir before refilling to remove any chance of puking the new pump..  When searching for my new pump I was seeing prices in the 8 hundreds,, kept looking online and found the right pump for $180.00 brand new delivered to my door..>>>Dan

[Jim Blackwood]

So using John's numbers his motor should run maybe 50% faster than the pump, which should be a pretty good fan speed if the pump is running at engine speed, which it may not be. You can get GPM from the displacement with a bit of math or maybe one of those online conversion tools. The pump doesn't care what your GPM is, the faster you spin it the more it will pump out so GPM is useless without a rotation speed to go with it. Displacement is a much more useful number. If your pump's displacement is too low it will run the fan too slow and system pressure will be low. If your fan's displacement is too low it will run the fan too fast and system pressure will be high. If both are too small system pressure will be high and may produce excess heat or actuate the pressure relief valve constantly. If both are too big the system will run ok but at low pressure and there may be more "slippage" in the system. Parts will be big, heavy and expensive and larger hoses and lines will be required.

Vane type pumps will not produce as much pressure as gear pumps and the one in the photo looks like a gear pump to me though I could be wrong. If it is a gear pump, it does not care what the running pressure is either. It will happily go over 5 Kpsi if flow is restricted, limited only by the pressure relief valve. Whichever type it is the motor needs to be a match in displacement and preferably in type. Aside from a simple pressure relief valve (Useful if the fan gets blocked) what controls you include are dealer's choice. Nothing more is really required except a good reservoir, filter, and cooler. Clifford and John's numbers might help in deciding what pump and motor are needed, or maybe what motor will work with your pump and from there what lines to use.

I'm not so sure on the buses but on lighter vehicles power steering pumps put out a considerable volume usually around 1000-1200 psi of pressure (.6 oz displacement IIRC) and some mfg's use the ps pump to drive the radiator fan also. Not sure how much hp that big fan draws but I'm surprised to hear it's that much more than the PS takes.

Jim

[luvrbus]

Hydraulic motors are HP rated for the load, rule of thumb long ago in class was 1hp per 1gpm @1500 psi that has probably changed over the years ,I know my fan motor was rated up to 22 hp

[Iceni John]

So using John's numbers his motor should run maybe 50% faster than the pump, which should be a pretty good fan speed if the pump is running at engine speed, which it may not be.
Jim

Don't forget that my pump is also supplying the steering box through a priority control valve, so that's why the radiator fan doesn't turn faster than the engine speed.   The pump is driven off the left (passenger) side camshaft, which being a 2-stroke is the same speed as the crankshaft.

John