reverse rotaton pump mount

[muddstopper]

Not having to measure to know the engine crank is much bigger at the rear than the pump shaft. Not sure if crank is cast or forged. At any rate if the crank can pull a 2 ton truck loaded, I am reasonably sure it will pull a hyd pump. Now if your talking about using the front of the crank for direct coupling of the pump, there would be a major difference in bearing size of the crank between front bearing and rear bearing, and just assuming a 7.3 crank is similar in design as a gas engine, the end of the crank is machined down to accept the harmonic balancer and might not be much larger than the pump shaft. I too have seen a lot of engines with pumps mounted on the front, trash trucks, ditch witches and farm tractors to name a few. A few concerns I have, granted I dont have the engine setting in my shop to actually look at, would be pump clearance. A double pump is pretty long by design, using a universal joint coupling or even lovejoy type, would make it stick out even further from the engine. Then you still have to have room for the radiator, or raise the radiator so the pumps will fit under it. I havent decided which way I will go yet for mounting the pump, just have to get everything in the shop and sort it out. I am heavily leaning to making a mount to put the pump on the rear. The 7.3 medium duty trucks use a adapter between engine and transmission to accept a sae 2 or 3 bellhousing. I am hoping I can build off this adapter, but I havent actually looked at it so who knows.

 

[CJONE]

I haven't seen a cast crank in a large diesel or any diesel for that matter. 2000 and up are PM rods but that is not a issue for you. Your going to have to keep the engine at the desired RPM and we have always done that with a pto [electronic] controller in the ford 350-550 trucks I normally work on. I have had a few 7.3's apart and if you drive the pumps directly inline with the crank you should have no issues with the front main. If you run your pumps at 3k you will need 150 EBH and you will be hard pressed to belt drive it and I would be worried about the front main taking that much of a side load. Rear drive with a chain coupler and solid mounts would be fairly simple but is that the right rotation for your pump? CJ

 

[muddstopper]

Yea, the guy I got the pump siad it was reverse rotation, and I am sure he knows as he's been building and designing big equipment for years. Before he sent the pump to me, he took it apart to change rotation and said it couldnt be done without buying parts that cost as much as the pump. Pump was a freebe, so its what I am going with.

Pumps only need to turn 1750rpms to get advertised flows, I am sure I could turn the rpms up if I thought I needed it, but its already borderline to big as it is. I believe the 7.3's peak hp at 2000rpms, so I should be pretty close to more than enough hp at 1750rpms. I will most likely just use a throttle stop and set the engine at 1800+/- rpms. Max hp shouldnt be needed as all funtions are short bursts of flow and then noload. Cyl retraction and should be at near nothing pressure wise and very seldom should the cyl see max pressure as they extend. I just about bet the unloader valve set at 2000psi will hardly ever have to unload. I just want the extra power for when I might need it and then the unloader will be dumping almost half the oil back to tank and the little larger section (about 42gpm) would build max pressure. So it isnt going to take all the hp the engine can produce. Probably wont need over about 125hp with everything maxed out which would be very seldom. I would have to be sawing at max pressure and at max splitting pressure to even get close. I dont think I can work that fast, or that hard anymore.

 

[oldnslo]

mudd,
I was talking about the front or fan end of the engine. Yes you have to work around the radiator and it does make the engine much longer. That is why the bumpers on cement trucks extend out so far.

 

[muddstopper]

mudd,
I was talking about the front or fan end of the engine. Yes you have to work around the radiator and it does make the engine much longer. That is why the bumpers on cement trucks extend out so far.

I have already been considering how to work around the radiator and havent came up with any good ideals. I think at a minimum, I would have to raise the rad enough to fit a drive shaft under it and that would put the pumps way out front of the rad. I would still have to mount pumps at the rear to run all the aux functions. Since the pump is reverse rotation, I think it would be better to just make some sort of belt or chain drive and turn the pump around and mount it beside the engine, I then could either drive the aux pumps from stub shaft on the engine, or the jack shaft for the main pump, or possibly, just depending on what aux pump I find, maybe mount it on the front of the crank. I would like to find another ditchwith backhoe attachment pump, like the one I had planned to use but let get away, for the aux circuits.

 

[bigdeano]

Maybe you could use some kind of gearbox on the back of the engine. That's a lot of hp for a belt drive.

 

[muddstopper]

I have been looking for a pump drive gear box, thinking I might find one on a old t9 dozer that might bolt to the back of the 7.3. I have found some new gear boxes, but I aint interested in paying the $7-8000 they want for a new one. I even thought about taking the inputs shafts out of a couple of transmissions and building a gear box. Not sure my machining skills are up to that task. Cant do much planning or building until I get time to get the truck home and the engine pulled and that might not be until spring. According to a few diesel sites, the 7.3 uses a SAE 2 or SAE 3, bell housing bolt pattern, which might make finding a pump mount gear drive a little easier. I just cant get a positive answer to the actual bell housing mount size or any detailed drawing of the bolt pattern for a 7.3.

 

[bigdeano]

Search for Velvet Drive transmission on ebay. They're boat transmissions. I think they have forward and reverse with the same ratio. Some of them are 1:1 ratio. They look pretty simple, but I don't know anything about them. Some of the used ones aren't very expensive.

 

[muddstopper]

Did a little reading on the Velvet drives. The model 71 seems to be the only one that is direct drive 1:1. One of those would probably work and I seen a few on ebay in the $300 range, used, so not that bad expensive. A few concerns I would have using one in my application is overall length. I would also have to come up with some sort of adapter to connect it to the engine crank. I would also still need to build some sort of mount for the pump and a driveshaft to drive it with. Time, work and money, I might still be better off to just build my own. My concern with doing a belt drive would be belt slippage, but I know of a few set ups on equipment where belts are used to power some pretty big variable pumps. I might copy one of those designs. If I recall correctly, there are two large, 80+gpm variable pumps behind a JD engine and there is either 3 or 4 belts to each pump, but I will just have to go back and look at it again to know exactly how its all connected. I have had to replace those belts a few times over the years, but that equipment runs 10 hrs a day 40 hrs a week and its several years between replacing belts.

 

[Rustyiron]

Tranny is shot before someone suggest using the transmission to reverse shaft direction.

I wonder if;
1 it has a PTO acess & if IT would still work
2 would it (pto) provide the proper speed for your pump.

Nou sure how you would check this for operation without actually bolting on a pto unit. Maybe a good trans guy would know. The pto "box" would not be that expensive a way to go if it would work.