642 hydrostatic pumps

[renopker]

I'm in process of doing the pumps and wanted to know what the big spring in the rotating assembly does and why cant it be taken apart.

 

[OldMachinist]

The spring puts pressure on the pistons in the rotating group. I see that the repair manual says not to remove the snap ring, washer and spring and my only guess is that it may be under tension and requires a press or fixture to re-assemble.

 

[Tazza]

The spring puts pressure on the pistons in the rotating group. I see that the repair manual says not to remove the snap ring, washer and spring and my only guess is that it may be under tension and requires a press or fixture to re-assemble.

Its not meant to be pulled apart because there is no reason to, unless the spring is broken.
The way the manual shows to do this is to use a bolt and nut with 2 washers to take the load off the snap ring.
Good luck with your repair!

 

[renopker]

Its not meant to be pulled apart because there is no reason to, unless the spring is broken.
The way the manual shows to do this is to use a bolt and nut with 2 washers to take the load off the snap ring.
Good luck with your repair!

Does anybody have a junk rotating assembly.I need to find the spring rate at the installed hight.

 

[Tazza]

Does anybody have a junk rotating assembly.I need to find the spring rate at the installed hight.

Exactly what do you need to know? i have an old set here with scoring on the face.

 

[renopker]

Exactly what do you need to know? i have an old set here with scoring on the face.

If you take the spring out measure how long it is (uncompressed) .2 measure how long it is when it is installed, 3 then put the spring on a bathroom scale in a drill press and push it until you are at the install height,now the reading on the scale ,that's the number I need (spring rate)Or if you have two springs?Thanks

 

[Tazza]

If you take the spring out measure how long it is (uncompressed) .2 measure how long it is when it is installed, 3 then put the spring on a bathroom scale in a drill press and push it until you are at the install height,now the reading on the scale ,that's the number I need (spring rate)Or if you have two springs?Thanks

Yikes! What makes you think the spring may have lost its tension? The spring is there to hold the rotating group on to the valve or wear plate. There really is no reason for it to loose spring tension or break, it doesn't compress very much at all, no more than say 1/4” They won't get hot enough to damage the temper, and if they did, not just the spring would have failed, the pistons would have worn as well, i have seen one that this hapened to!
As long as the valve plates are flat, without scores and the rotating groups are flat, without scores too, you should be fine.

 

[renopker]

Yikes! What makes you think the spring may have lost its tension? The spring is there to hold the rotating group on to the valve or wear plate. There really is no reason for it to loose spring tension or break, it doesn't compress very much at all, no more than say 1/4” They won't get hot enough to damage the temper, and if they did, not just the spring would have failed, the pistons would have worn as well, i have seen one that this hapened to!
As long as the valve plates are flat, without scores and the rotating groups are flat, without scores too, you should be fine.

Fire has a way of annealing springs and bolts, it got hot enuff to melt the blower ,gov ,intake manifold all the hoses. the pistons are fine (in the pumps) but all the bearing, seals, are junk good thing the bearings are cheap.Even the valve,and port block springs were junk.and the one spring in the port block was 20.00

 

[renopker]

Fire has a way of annealing springs and bolts, it got hot enuff to melt the blower ,gov ,intake manifold all the hoses. the pistons are fine (in the pumps) but all the bearing, seals, are junk good thing the bearings are cheap.Even the valve,and port block springs were junk.and the one spring in the port block was 20.00

heres the pumps at the get go.

 

[renopker]

heres the pumps at the get go.

and heres the valve before and after.

 

[Tazza]

and heres the valve before and after.

Wow, you had a serious fire there! Thankfully it wasn't TOO hot, or the alloy case would have melted too. Hopefully the rotating groups and shafts are ok though.

 

[renopker]

Wow, you had a serious fire there! Thankfully it wasn't TOO hot, or the alloy case would have melted too. Hopefully the rotating groups and shafts are ok though.

Tazza I still need the spring pressure ,it can be done by putting the piston block on a scale in the drill press ,use a washer and push down with the press just a bit and note the scale .If you go to far it will coil bind .

 

[Tazza]

Tazza I still need the spring pressure ,it can be done by putting the piston block on a scale in the drill press ,use a washer and push down with the press just a bit and note the scale .If you go to far it will coil bind .

I'll see if i can do it Saturday, things are a tad busy....
Not too sure how acurate the scales are either, see what i can work out.

 

[Tazza]

I'll see if i can do it Saturday, things are a tad busy....
Not too sure how acurate the scales are either, see what i can work out.

Guess who forgot.....
I'll do my best to do it tonight when i get home from work.

 

[renopker]

Guess who forgot.....
I'll do my best to do it tonight when i get home from work.

Well the bearings arrived today and the seals will be hear wednesday Im getting excited let me know Tazza. Thanks

 

[Tazza]

Well the bearings arrived today and the seals will be hear wednesday Im getting excited let me know Tazza. Thanks

Nice!
I'll do it tonight, i keep getting distracted BUT i have written a note, hopefully it will work.

 

[Tazza]

Nice!
I'll do it tonight, i keep getting distracted BUT i have written a note, hopefully it will work.

Ok, i get 15.6/15.8 KG
That is using a socket and when it makes the spring compress enough to clear the snap ring. That is using digital scales, naturally reset with the rotating group and socket added so it was zero.
It seemed a little low to me, but its the figure it gave me...
Hopefully that is the number you want, and yours match or exceed it.

 

[renopker]

Ok, i get 15.6/15.8 KG
That is using a socket and when it makes the spring compress enough to clear the snap ring. That is using digital scales, naturally reset with the rotating group and socket added so it was zero.
It seemed a little low to me, but its the figure it gave me...
Hopefully that is the number you want, and yours match or exceed it.

THANKS now that wasn't so hard, It really helps I owe you one .remember I am 4 hr from the factory and any part I can have in 2days it might take longer to get to you.

 

[Tazza]

THANKS now that wasn't so hard, It really helps I owe you one .remember I am 4 hr from the factory and any part I can have in 2days it might take longer to get to you.

The hardest part was gaining access to the drill press! i really need to clean up a little
Hopefully the figure is rite, or at least close enough.