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MCI 102-C3 coach to RV - Engine Bay

CarterKaft said,

At these flows and speeds you may want to look at piston pumps as well.

A pressure compensated pump might simplify the control circuit using the wax motor as well.
 
aczlan said:
Max speed is 3000RPM though...

Aaron Z​
Precisely. None of them indicate that they can handle 5,000 RPM. And I have to have front and rear pumps of the same displacement which isn't doable on the stacked pumps.
CarterKaft said:
At these flows and speeds you may want to look at piston pumps as well.

A pressure compensated pump might simplify the control circuit using the wax motor as well.​
Axial piston pumps were the first that I went through. The speed and pressure capability along with the cool factor. Pumps with variable displacement were so costly that they got taken out of the running. Perfect match with the thermo valve, though. If I can find one...
 
Almost forgot to mention that I started running the numbers for 22" T3 8-blade fans with 35 degree blade pitch. At both 2,500 and 3,000 RPM. Significant drop in ponies required to spin them.
 
aczlan said,

Is the current power steering pump running on a different speed drive port (perhaps one that is 1:1 with the engine RPM)?
If so, would it be easier to find a smaller pump that can run 5000RPM and move the power steering to by the alternator and put the fan pump(s) where the current power steering pump?
If not, your best bet might be to belt drive a pump off of the accessory drive by the alternator and use pulleys to reduce it to half the speed.

Aaron Z
 
Both pump drives are on a 1:2.05 ratio relative to crank speed. One spins counter-clockwise and the other spins clockwise as viewed from the flywheel end. I'm not sure why they were made to spin that fast unless they were only ever intended for a very small displacement pump. The Vickers steering pump is tiny.

Found: Rexroth AA10VG18 axial piston pump will operate, without detriment, in all engine RPM ranges. Constant max of 4,000 and intermittent of 5,200. Downside is that it's only 1.1 cu. in. Upside is that at it's displacement, max RPM and pressure, it does actually come in just under the HP needed to spin all four 22" T4 8B 50 deg. fans at 2,500 RPM. But, this is at just over 5K PSI. If I can acquire one of these pumps at a reasonable price, I'll knock the fan blade pitch down to run within system specs.

I'm guessing that even the smallest of the VG pumps is still for an SAE B pattern. Machining and adapter is easy. Beefing up the pump drive might take a little more ingenuity.

Edit: AA10VG18 is discontinued. If I didn't need 400-1,000 amps to power electric motors for this, I'd likely revert back to that.
 
Today's findings -
I spent most of the day charting fan and pump HP. Rather than attempting to fit some monster, high-end pump to drive four fans at such high RPM and pressures, I began with filtering pumps that would be a direct or near direct fit to the SAE A flange and 3/4" straight shaft. Ended up a little bigger.

Pumps:
Front - Prince 2.008 cu.in. that will drive two series 22" T3 8-blade fans with 50 degree pitch.
Rear - Prince 1.220 cu.in. that will drive two series 22" T3 8-blade fans with 40 degree pitch.
The T3 blades can be removed from the hub, so to save weight and cost, I'll simply change out hubs if I find that I can lessen the pitch to reduce the load.

Motors:
Outside - Hydreco 2.440 cu.in.
Inside - Salami 1.530 cu.in.

I have the figures set up to drive the fans around 2,500 RPM when the pumps hit 3,000 RPM (about 1,500 engine RPM) so that the fans can run full bore without having to redline the engine when it's already hot. System pressures only need to be 1,100 PSI in front and 950 PSI in rear to supply the torque and horsepower to drive the fans at full speed. The pumps are only stated to be good for 3,000 and 3,500 RPM, but I'm going to give them a go as I'm having to assume that their max RPM is while at max PSI of 3,000 and higher. Their inlets look to be big enough to avoid cavitation during brief moments above 4,000 RPM.

I'll have to set up some kind of flow restriction or diversion to keep the fan motors from over spinning. Perhaps the pilot-operated valve can be worked with to do so. So far, total power draw from the engine comes to 56.8 HP.
 
Elwenil said,

And all of this is going to be more reliable than a belt?
yH5BAEAAAAALAAAAAABAAEAAAIBRAA7
 
Elwenil said:
And all of this is going to be more reliable than a belt?​
Maybe? I’ve been seeing posts about fan belts lasting as long one million miles and as little as 10k miles.
 
Elwenil said,

I know it's more complicated that it seems with a pusher and the radiators on the side, but with all the calculations, various parts, stacking this, keying that, flow here, RPM there, a couple pulleys and a belt look mighty simple. Probably a lot easier to fix when it breaks on the side of the road too.
yH5BAEAAAAALAAAAAABAAEAAAIBRAA7
 
Elwenil said:
I know it's more complicated that it seems with a pusher and the radiators on the side, but with all the calculations, various parts, stacking this, keying that, flow here, RPM there, a couple pulleys and a belt look mighty simple. Probably a lot easier to fix when it breaks on the side of the road too.
yH5BAEAAAAALAAAAAABAAEAAAIBRAA7
No doubt. I totally agree that a belt swap is easier than anything else. On the flipside, I've grown to have an aversion to belts flapping around near my appendages while working on a running engine. Most of what drove me to do this was the efficiency advantage of hydrostatic and electric over a belt drive that operates the equipment 100% of engine operating time and it being entirely dependent on engine speed. Second was ease of access. I will no longer have large coolant pipes snaking all around the engine bay or have to deal with how crammed every other component was. Calculating all these numbers to get it right was a step MCI/Detroit had to take as well, I'm sure. Since they didn't build this setup, I had to. I must say the maneuvering in and around the engine bay is so much easier now. Give or take, roadside repairs will be pretty easy. Of course, I could have left everything alone and gone down the road fine for the most part. The cooling still needed work and all in all I'm pretty happy with what I mentioned above. We'll see what comes of it.
 
Elwenil said,

I get the nervousness around moving belts. I have waist length hair, so I am more than a little paranoid leaning into an engine compartment, even if the damn thing is off, lol.
 
Elwenil said:
I get the nervousness around moving belts. I have waist length hair, so I am more than a little paranoid leaning into an engine compartment, even if the damn thing is off, lol.​
Lol. My hair is only shoulder length and it gets scary. Got it sucked into the fan of a palm sander years ago and I thought my friend on the other side of the shop threw a football at my head.
 
As it stands, my only locations to drive a belt from are the 8" and 9" crank pulleys and the 6-1/4" left cam pulley. Crank and cams spin at the same speed. Making a bracket that would track the belt correctly would be the hardest part. It'd need some shimming. All the mounting surfaces are rough cast. The cam pulley would be the only practical drive. I'll have to see if there are any pictures of accessories driven off the cam. From the looks of it, belt routing would be a quite awkward.

Alternator would be driven off the cam pulley, I'm told.

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Coincidentally, this was just posted showing something driven off the cam pulley. Looks like a small AC compressor.

2913876-96bca514a702bd2da856b3625723cb27.jpg
 
Some may recall the “BUS DUTY” motors I pulled off the bus. Already 27 volt. 55 amp and 2,900 RPM. We’re thinking of ordering one fan to try out on the single shaft motor. These things were turning fans with about as much CFM before. Worth a shot.

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Just reporting some good news on the days to come.

First off, I called Knob Hill Towing again about getting our bus on a Landoll trailer to haul up to Springs. Got transferred to the driver and no sooner than the words "It doesn't run, so it won't air the suspension up" came out of my mouth, he said "No, we won't do that". End of conversation. We found JE CO Inc. out of Denver. Called and had a really good chat with the receptionist (owner's wife, I do believe). They're all for it and we'll be going over more details on Monday. Rough quote of $1,200 to drive down here, load the bus and drop it at the new house. They can do it as soon as two weeks from now.

Second call - Hoverhawk owner said the T3 hubs are all the same, (T4 adjustable hubs are 10" in overall diameter). The blade pitch is changed by ordering the specific blades. That's in my favor. He also said the 2,900 is an excellent speed for the fan to do the work. I'll order a 22" T3 8-blade on Monday to try out on the single shaft motor. With the optical tach, IR thermometer and clamp meter, I'll see how well the motor does to move the fan and possibly put up a large section of window screen to simulate pressure/vacuum. If 8 22" blades is too much, I'll take four off and/or go for 20" blades if need be.

If, and this is entirely IF the OE DC motor works, I'll be using Dart Controls 65E60 PWM. They have every feature included that I would be after and can handle the stated running current with ease. The Delco alternator has room for all four motors, too.

I'll be ecstatic to get the bus up north. High of 30 degrees here today while it was 60 degrees in Springs. We had a 50mph blizzard with a low of -20 the other night and the bus now looks like this inside...

435.jpg
 
[486] said,
JNHEscher said:
Rough quote of $1,200 to drive down here, load the bus and drop it at the new house. They can do it as soon as two weeks from now.​
is the cooling system the only reason you can't drive it?

I'd pipe up an IBC tote in there with water in it and drive it if that is the case
 
[486] said:
is the cooling system the only reason you can't drive it?

I'd pipe up an IBC tote in there with water in it and drive it if that is the case​
It's not. All air, fuel, coolant and oil lines are out. Too much to get done in too little time. Lots to wire back up as well. That'll all be so much easier to get done near Springs since I'll be a ten-minute drive away from all the hardware and parts.
 
vetteboy79 said,

Tried looking back but the search function sucks...did those bus duty DC motors come from a squirrel-cage application previously?

If so, just be sure to consider that your application with the fan will have primarily thrust loading on the rotor shaft...not all motors are designed for that.
 
vetteboy79 said:
Tried looking back but the search function sucks...did those bus duty DC motors come from a squirrel-cage application previously?

If so, just be sure to consider that your application with the fan will have primarily thrust loading on the rotor shaft...not all motors are designed for that.​
The through-shaft motors run a dual squirrel cage for the passenger evap. and heater core. The single shaft motors use a thrust fan for condenser cooling with the shaft vertically oriented. Depending on the room I have, I may mount the fans directly on the motor shafts or still run the fans on their own shaft coupled to the motor. Kinda like the idea of fans on their own shafts so that motor de-coupling is quick and easy and fan weight and balance is isolated from the motor.
 
Not much to report lately as we’re just awaiting house paperwork finalization and getting the bus ready for the tow. While in Denver the other day, I grabbed bearings for the potential fan motor and then called U.S. Coach to order the brushes.
 
One major move accomplished. We've been in the new house for a couple weeks and just got the bus hauled to it last night.

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456.jpg
 
I think I've said this several times by now, but we are ordering a fan from Hoverhawk on Monday. Got the go ahead on all fronts. If I remember correctly, 22" diameter, T3 hub, 8-blade, 35 degree pitch. Hoverhawk has that exact same configuration in both pressure and thrust fans at 3,600 RPM. The only stated difference is the CFM. I'll discuss with the owner which fan would be best our application or if the measurements are just so different because of vertical and horizontal use.

Put one bus battery on the charger to see if it brings it back to life. Maybe parallel the batteries so I can charge them both together. Going to start setting up for mounting the motor on a table edge, change out bearings and brushes then wire it up. Have to figure out where I put all my measuring instruments.

Any last words before I make the call for that specific fan order? Got a day and a half to scratch scalps about it and wait for snow melt since there's still three feet of it against both my tables outside (which are also three feet tall).
 
aczlan said,
JNHEscher said:
I think I've said this several times by now, but we are ordering a fan from Hoverhawk on Monday. Got the go ahead on all fronts. If I remember correctly, 22" diameter, T3 hub, 8-blade, 35 degree pitch. Hoverhawk has that exact same configuration in both pressure and thrust fans at 3,600 RPM. The only stated difference is the CFM. I'll discuss with the owner which fan would be best our application or if the measurements are just so different because of vertical and horizontal use.

Put one bus battery on the charger to see if it brings it back to life. Maybe parallel the batteries so I can charge them both together. Going to start setting up for mounting the motor on a table edge, change out bearings and brushes then wire it up. Have to figure out where I put all my measuring instruments.

Any last words before I make the call for that specific fan order? Got a day and a half to scratch scalps about it and wait for snow melt since there's still three feet of it against both my tables outside (which are also three feet tall).​
I think I lost track somewhere, you will be re-using the electric fan motors that were on the squirrel cage fans before?

Aaron Z
 
aczlan said:
JNHEscher said:
I think I've said this several times by now, but we are ordering a fan from Hoverhawk on Monday. Got the go ahead on all fronts. If I remember correctly, 22" diameter, T3 hub, 8-blade, 35 degree pitch. Hoverhawk has that exact same configuration in both pressure and thrust fans at 3,600 RPM. The only stated difference is the CFM. I'll discuss with the owner which fan would be best our application or if the measurements are just so different because of vertical and horizontal use.

Put one bus battery on the charger to see if it brings it back to life. Maybe parallel the batteries so I can charge them both together. Going to start setting up for mounting the motor on a table edge, change out bearings and brushes then wire it up. Have to figure out where I put all my measuring instruments.

Any last words before I make the call for that specific fan order? Got a day and a half to scratch scalps about it and wait for snow melt since there's still three feet of it against both my tables outside (which are also three feet tall).​
I think I lost track somewhere, you will be re-using the electric fan motors that were on the squirrel cage fans before?

Aaron Z​
Correct. It's actually the single shaft motor from the OTR AC condenser fan. Hooked it up and tested it in as is condition today. Runs like a champ, but the bearings are in dire need of replacement. Brushes are good for now though I should clean the bars. I'm going to document current draw with and without load. At the moment, this is just to see if using the OE electric motors is a viable alternative to that hydrostatic mess. I'm imagining a lot less maintenance. The motors being brushed DC allows them to reversed with a flip of a switch. Kinda handy for cleanout and either fan rotation can be ordered without concern for shaft rotation or motor position.

So I thought I was going for a 35 degree pitch. I found my notepad that had my latest to do list entry. It says Hoverhawk 22" T3 8B 50 deg. Think I'll go with what the owner suggests when I call. Last time I talked with him, he said go with the largest diameter I can fit and the steepest pitch.

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Hells bells. Put in the order for the Hoverhawk fan. Got the receipt this morning saying it would be ready to ship in about two weeks. I need to put a whiteboard back up so I can keep a list of items to successfully work on while waiting for parts to arrive. For that matter, I suppose I could take a Sharpie to the side of the bus. That snow needs to melt, too.
 
Been digging through coolant temperature sensors and thermistors in general. Can't come up with impedance ranges on any sensor found on Summit Racing, even when checking manufacturer sites. I have a couple sensors for Detroit Diesels pulled up. They're inexpensive, but still no ohm ratings. Might order one of each to test. The one thermistor I have found to be pretty much a perfect unit is an Omega 44008. It's already NPT and has the correct values to use in place of the 5K pot required to vary the input voltage on a Dart Controls 65E60 PWM controller. $74 each, though.

All ports on the engine are NPT. Most are 3/4". If need be, I can certainly weld a straight thread bung on a coolant pipe to accept o-ring style sensors. I'm after a set of suitable thermistors to operate the PWM controllers to adjust motor RPM based on coolant temperature alone.
 
Satan's_Minion said,

That condenser motor is MAYBE 1-1.5kW so it is not going to be able spin any of those big blades very fast. Also you need to understand the air side operating point of the cores you are using to pick a good fan for it and know how much power you will need to spin it.

New bus applications transit to coach with electric fan use between 4-8 kW of electric fan power with much more efficient cooler technology but different heat rejection requirements. Factory systems are designed to run at 100% power continuously though, so a home built system and operator could likely get by with less.
 
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