Taking hydraulic motor apart for new seals

[Richard]

Ok, so pulled out my calipers.

I got some differences in my readings (I'm not an expert on its use, especially for a critical measurement like this)

Put the caliper inside from 12-6:00 and then turned it 90 degrees to check 3:00-9:00. Did this for the bore and the rod/gear.

For the drive gear, I pretty much got 31.8 mm for both directions. For the drive shaft that fits that hole, I got 31.69mm

For the second bore I got 31.6 both directions and for the idler gear, I got 31.64.

When you put them in the bore there is a slight wiggle to them. Not knowing if that's right or not, it seems slight. Either way, they appear to be pretty round verses ovaled in my eyes.

 

[ptsg]

I'm sure it has some wear, it's just the nature of it.

The gears are hardened so they will show very little wear, if anything at all, although I can spy a bit of wear where the shaft seal rides on but no big deal.

The aluminium housing will take the most beating. It's hard to tell on the pictures without looking at it in person and doing the mandatory nail scratching wear assessment. But it doesn't look terribly bad. That seal you found, I'm sure it wasn't helping anything.

At this point, since you have the seal kits already, just put it back together with the new seals and see if it made any improvements. It's not that there is much to be done on the wear of the aluminium parts.

 

[Handloader109]

While it might be the motor or motors, nowhere did I see that you careful checked all the interconnected hoses for any obstructions. You could have old hose collapsing on one side. And which order does the pump feed the motors? I bet the one running best is fed first......

 

[Richard]

doing the mandatory nail scratching wear assessment.

Quick response: I have simply put all the goodies into a box to take to the repair shop for them to evaluate. I need to go there anyway (with the old replaceables, I do not yet have the replacement parts....this is why I was disassembling the unit) so why not take the housing to see if they'd give an opinion on it first hand.

That said, I did happen to do the fingernail test. There was one side of the bore that caught the nail and the other side was pretty smooth (though might have caught the nail every so slightly. Point being, between the two sides, there was a difference.

While it might be the motor or motors, nowhere did I see that you careful checked all the interconnected hoses for any obstructions. You could have old hose collapsing on one side. And which order does the pump feed the motors? I bet the one running best is fed first......

I've not even glanced at the hoses! (full disclosure)

I know that one of them needs replaced and that's on my list during this tear-down. It actually has some of the wire reinforcement not only exposed but rusted and slightly unraveled a bit. Every time I go cut I just fear that it's going to blow and create a huge mess. I doubt I'll use it again now, prior to replacing that hose.

I'm not exactly sure the flow path of the oil....does it come out to the left wing first or the right wing? Your comment was already floating in my head when I noticed the difference in cutting height/quality. Seeing the decaying hose however, told me that no matter what might be ahead of the motors, they still need attention and will take the longest so why not start there (since I had just cut the important field)

My game plan is to assess this motor. If I need to buy a new housing for it....then how much. If it's cost effective I'll anticipate having to buy three of them. If it's not cost effective, I'll probably replace the mower and scrap it. I don't mind if all three motors are weak and I have to cut slower.... but having one good one and two weak ones making have to cut things twice.....not going to fly.

A bit of a rhetorical question.....how does a hose collapse on one side? The hoses are pressure fed from the pump. It would take a suction situation to collapse a hose, no? That said (it was an honest question by the way) you are right, I've not considered them at all.

 

[ptsg]

Good call on taking the parts to the hydraulic shop Richard. Let us know how it goes.

I don't believe a collapsed hose would cause any issue, simply because there is no way it would stop 2500 PSI from pushing through so it wouldn't have collapsed in the first place. Now, if it was on the suction side of the pump, that's different, but would also affect everything else on the hydraulic system.

 

[Richard]

Throwing some spagetti on the wall of ideas here....

(and to Handloaders credit)

If I read the hose schematic correctly.... it would seem there is a 3/4" hose that goes directly from the pump to the center motor. Then, there is a 1" hose that goes from the left wing to the right wing (or vice versa) Point being there are two circuits.

How do I have a sudden issue with the center and one wing, especially if they're both on separate circuits? Happening to them at the same time strikes me as suspicious..... (though for a machine this old any rebuild is certainly in good order)

I think I'm going to get some new filters when I'm out next. I see that as a common connection point between the two of them AND I'm going to scrutinize the supply hose from the tank to the pump. I've never liked how it's mounted and it might be 12-18 inches too long....as I've noticed it has a slight kink in it from drooping down. When I first bought this unit, this specific supply hose was simply kinked with a distinct pinch point where the prior owner would fold the pump back to lay it on the mower and that caused this pinch point. I replaced the hose day 1..... and for practical purposes have never taken the mower off the tractor (not literally true but it's only been off 3-4 times) so the replacement hose doesn't suffer that folding back/forth BUT not knowing how long I needed I bought it long and cut to size. I still think it's a touch long and when I turn, crowding it, a folding point has been created.

I'm wondering if I have a simple starvation issue from that, in addition to weakened motors?

When I first used this mower (prior to purchase) and once I had it mounted on my tractor, I was amazed at how well it shredded anything in its path. So to go from a monster shredder.....to two motors going wonky at the same time IS starting to make me broaden my field of suspicion.

 

[wdchyd]

Looks like an M20 series Tyrone motor. Now owned by Parker.

 

[Richard]

Looks like an M20 series Tyrone motor. Now owned by Parker.

How awesome is this... I take all parts 45 miles away to the pump shop... Walk in as I'm setting the box down talking to the manager...I tell him that someone suggested this was a Tyrone M-20.... As this is happening another customer walked up behind me... overheard the conversation and confirmed it was. As it turned out he wasn't a customer but rather one of their product reps who was stopping by to see someone.... Said he's rebuilt hundreds of these and recognized it immediately!

Sales guy now knows for sure who to call and now, three sets of gaskets aro being drop shipped to my home so I won't have to drive back to pick them up!

He said he'd probably reuse the housing again and seen much worse

 

[Richard]

Here's a question for you....

Shop guy said he'd use something like "honey oil" or what he said was something like STP building oil. I know generally of what he speaks.....very thick and you use it as you're rebuilding an engine or something so it tends to stick in place for initial startup.

Went to NAPA and now that I'm home, I see she gave me something like "Purple Crown engine break in oil"

I'm thinking these are two different things (and maybe it doesn't really matter?? Which is my question)

Should I just use this after spending about $11 on it....I can use it for all three motors. Or do I go get the STP type stuff which she evidently didn't have.

 

[wdchyd]

It’s not gonna hurt, most places won’t use anything but #2 grease on the brass thrust plates, du bushings and seals while the hyd oil is priming. It’ll all wash away once it gets oil moving. Best run things slow at first without a load.