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why did this hose blow?

marcin

Active Member
Joined
Mar 3, 2013
Messages
34
Location
texas
Hi all,

I was hoping to get your opinion on this. I own a JD 750 C series 2 dozer. Last summer, I had the transmission pumps and motors rebuilt. Since that time, I have had one of the hoses to the left motor fail twice. The first time, it was just a small leak. The second time, the hose burst at the crimp - please see the attached photo. This is a high pressure hose (5500 PSI). I was hoping you could give me your thoughts on this - is there a problem with the motor rebuild or the way this hose was made? I used the same new place to make this hose (both times). Thanks.

IMG_1851.jpg
 

partsandservice

Senior Member
Joined
Feb 14, 2011
Messages
846
Location
Georgia
Can't tell for sure from that picture, but I bet it is the wrong kind of hose. A six wire hose is necessary in this spplication, what you have is likely a 4 wire. Operating pressure on that hydrostatic system is about 5000 psi or better calling from memory. That does not account for momentary pressure spikes. Cut that hose and count the layers.
 

Nige

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Jun 22, 2011
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G..G..G..Granville.........!! Fetch your cloth.
It says 5500 PSI on the hose, is that not enough?
Judging by the way it let go, probably not. The 5500psi could be bursting pressure as opposed to working pressure. As P&S suggested, cut into the hose and see if it has 4 or 6 layers of wire reinforcement.

However all joking aside, does it give any SAE reference apart from the "5500psi". Something like SAE100R2 for example..?
 

td25c

Senior Member
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Feb 14, 2009
Messages
5,250
Location
indiana
My first guess looking at that photo is that there was something wrong with either the hose-making machine, or the person driving it, or both.

I tend to agree Nige .

Or possibly wrong fitting & crimp collar ?

Just looking at the way the hose swelled evenly at the failure makes me think it's not a snug enough crimp allowing the hose wire to slip & expand behind the fitting ?
 

Jonas302

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Jan 4, 2015
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Location
mn
We tend to get equipment hoses at there respective dealer when its possible its cheaper and faster in the long run
 

Truck Shop

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WWW.
Went through this same deal this last summer. Regular guy that made the hoses was on vacation, person operating hose press used the wrong collars.

Truck Shop
 

CavinJim

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Joined
Nov 28, 2016
Messages
170
Location
Missouri
Folks kept telling me to get hoses made at the local auto parts store. I got a quote from them and compared it to the local Deere dealer. Deere was far, far less expensive! I got four hoses from deere for what just one was going to cost at the auto store. The issue was that the auto parts place doesn't normally stock the larger, higher pressure fittings these crawlers need. Be very suspicious if it wasn't a shop that deals with big iron.
 

old-iron-habit

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Moose Lake, MN
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The crimps on the failed end do not look to deep. Wonder if the machine pressure is set properly for the hose or if the correct high pressure end was used. Being a new shop I would suspect any of the above.
 

lantraxco

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Jan 1, 2009
Messages
7,704
Location
Elsewhen
May just be the usual case of a high hour machine, rebuild the pumps and motors so they're making full pressure and pretty soon the old hoses show their tiredness as well. Might pay to have the dealer do a quick check on the pressure limiters/reliefs. Sometimes pressure spikes happen and the failure point is almost always at the crimp if there are no damaged spots in the hose cover elsewhere.
 

marcin

Active Member
Joined
Mar 3, 2013
Messages
34
Location
texas
This was a brand new hose, actually the second brand new hose. The hose states SAE 100R13 DN25 - 1" - ISO 3862 WP MSHA IC 252/00 - 4Q14
 

CavinJim

Well-Known Member
Joined
Nov 28, 2016
Messages
170
Location
Missouri
This was a brand new hose, actually the second brand new hose. The hose states SAE 100R13 DN25 - 1" - ISO 3862 WP MSHA IC 252/00 - 4Q14

I'm seeing that that's a 5000 psi hose. Curious--how long did the machine run before the hose blew? If the oil's getting too hot, the rubber softens and the hose will loosen in the crimp and POP!
 

partsandservice

Senior Member
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Feb 14, 2011
Messages
846
Location
Georgia
3862 WP , working pressure. I am reading that right? The correct hose is about three hundred from Deere. My money is on it being a four wire, which will never hold for long on high pressure loop running 5000 psi. Also the other hose to that motor will have the same pressure in it when pressure is on the other side of the loop. Also the right loop should have the same pressure but could be slightly different because it is a different pump. Did you replace all four hose from the same stock or just the one?
 
Last edited:

marcin

Active Member
Joined
Mar 3, 2013
Messages
34
Location
texas
The machine has been used less than 100h since the new hose has been put on and on this occasion we just started running it (<30min).
 

John C.

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That looks to me like a two wire hose and four wire hose is called for. What brand of hose and end fittings. Some manufacturers require the hose to be skived while others press over the outer cover of the hose. Also the crimp is supposed to be checked with a micrometer to ensure the dies have compressed the collar fully. The dies do wear over time especially when they are not lubed or greased. I've also seen people put four wire ends on two wire hose which ends with the type of blown ends that you see. The other issue is the hose may not have been pushed all the way onto the fitting leaving and space inside the collet. Was the hose lubed before pushing the fitting onto the end? Another problem involves the installing the hose with a hard bend on the fitting.

Burst pressure is supposed to be at a minimum three times the working pressures. A 5,000 PSI working pressure hose is supposed to have at a minimum 15,000 PSI burst pressure.
 

marcin

Active Member
Joined
Mar 3, 2013
Messages
34
Location
texas
This hose was 4 layer. Burst strength of 14000 PSI.

I call jd today. They said that the hose should have a working strength of 6800 PSI. They gave me a part number which is a Parker hose R15 - working strength of 6000 PSI, burst strength of 24000 PSI. So a little inconsistency there.

I went back to the hose shop. The crimp spec apparently checked out. The owner stated that there is no 1" hose that has a working strength greater than R15. Why the discrepancy between the working strength required and the specs of the part number? Thanks again.
 

Dickjr.

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Mar 24, 2011
Messages
1,484
Location
Kentucky
This may be getting into the dealer only type part or hose. The hose shop probably rarely sees a drive hose like this. I can say this much from experience , I replaced a drive hose on my 943 , the end were the lifetime type Cat has , mine were bad but they did not charge me for new ends. The section of hose about 4' long was right at 400$. Replacing that hose cost me 1500$ in parts labor and trans oil. I never did look at the working psi , and I hope I don't have to for a long while.
 

partsandservice

Senior Member
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Feb 14, 2011
Messages
846
Location
Georgia
I have been involved in this situation many times. An under " sized" hose will almost invariably fail at the crimp; just as the steel cracks again beside the weld. My intention is not to be rude. You have the WRONG hose. Get the OE hose or have them make a six wire hose. Your issue will be fixed.
 
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