Mini Motor Grader build - Page 11

Cubcadet_107 · #**101** 02-13-2021, 11:08 PM

Well, this is a very odd failure. Don't think I've ever heard of anything like this, usually when a hydro fails it's very noticeable what the problem is!

I was thinking perhaps the splines on one of the axles stripped out, but it sounds like that can't be if you still feel the resistance of the motor turning when you rotate the wheels.

But, by any chance, do you think the charge pump went out? Or perhaps the charge pump pressure relief? If the charge pump can't provide fluid to the drive pump then the system won't pressurize and it'll be able to roll freely.

Ambush · #**102** 02-13-2021, 11:38 PM

Rather than try to run and sync two hydro's would it be possible to put a drive line between the pinions? Remove the rear hydro and drive it with a pto type shaft with the front. Power is limited by your engine, so your not really giving up anything there. Looking at your build, you obviously have the skill and machinery.

sawdustdad · #**103** 02-14-2021, 07:21 PM

Quote:

Originally Posted by Ambush

Rather than try to run and sync two hydro's would it be possible to put a drive line between the pinions? Remove the rear hydro and drive it with a pto type shaft with the front. Power is limited by your engine, so your not really giving up anything there. Looking at your build, you obviously have the skill and machinery.

Syncing the hydros is pretty simple. Run a rod from one cam plate to the other with some length adjustment allowance. They don't have to be perfect, just close. I did the same thing with my Tandem build a couple years ago and it's working fine.

Ambush · #**104** 02-17-2021, 01:00 PM

One more question.

How the heck do you keep your shop floor SO CLEAN!?!

And congrats on finding what looks like a well looked after SB lathe. Rare find.

sawdustdad · #**105** 02-17-2021, 07:52 PM

Quote:

Originally Posted by Ambush

One more question.

How the heck do you keep your shop floor SO CLEAN!?!

And congrats on finding what looks like a well looked after SB lathe. Rare find.

Epoxy paint helps a lot...

The SB 10" lathe is actually pretty well worn in some spots. The saddle and cross slide have a good bit of backlash and the ways are a bit beat up near the headstock. But the headstock itself is solid and it runs and works OK. It was, I believe, a WWII Navy shipyard lathe based on the markings, vintage and the guy I got it from. I live about 75 miles from the Norfolk, Virginia shipyards and the guy who had it was a machinist for the shipyard. I'm guessing he got it surplus.

I got a SB 7 inch shaper in excellent shape about a year ago. It's not very practical but a blast to play with.

DRohacek · #**106** 02-21-2021, 07:26 PM

Frank: What size hydraulic hose are you using? Are they 3/8?

David.

sawdustdad · #**107** 02-22-2021, 07:55 PM

Quote:

Originally Posted by DRohacek

Frank: What size hydraulic hose are you using? Are they 3/8?

David.

All of the cylinder hoses are 1/4 inch, #6 JIC fittings. The hydraulic pump/motor assembly was all 3/8 inch hose.

BTW, I've abandoned that drive method at this point based on advice from Ambush suggesting that the gear drive pump and motor may contaminate my rear end reservoir. He also suggested a dual belt drive which made more sense. So that's where I'm headed now.

sawdustdad · #**108** 02-22-2021, 08:08 PM

Here's an early mock up of the dual pulley arrangement. I'm working on the tensioner which is complicated by the tight quarters, high speeds and dual belts. I think I've got it figured out, but I'm having to make everything. Thinking about a pillow block bearing along the shaft between the two hydros but probably more complication than needed.

Ambush · #**109** 02-22-2021, 10:13 PM

Looking good! If you do decide to use a bearing, rather than a pillow block, a two bolt flange bearing will be much easier to locate on the shaft center. I'm no good at computers, but I could do a quick sketch and take a pic of it to save trying to explain it. Though your pulley is mounted right up close to the charge pump bearing anyway.

sawdustdad · #**110** 02-22-2021, 10:57 PM

Quote:

Originally Posted by Ambush

Looking good! If you do decide to use a bearing, rather than a pillow block, a two bolt flange bearing will be much easier to locate on the shaft center. I'm no good at computers, but I could do a quick sketch and take a pic of it to save trying to explain it. Though your pulley is mounted right up close to the charge pump bearing anyway.

That's exactly what I have, a bearing in a two bolt housing that allows for some shaft misalignment. Was thinking about drilling and tapping the boss on the back of the forward axle, then shimming the pillow block bearing as needed. Only down side is I need to disconnect the shaft at the forward hydro to put a new belt on, so that's one more thing to deal with.