743 Major Repairs

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Tazza

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wear sleeve and wear ring are the same? did checked the chain links yesterday.. remember i mentioned before that 1 is longer than the other.. both has the same number of links.. so i checked the connections. the longer one has bad connections. there's a lot of play in every links thats why its longer. I have good news found the remaining bearings.. now i need to follow up on the chains. got 10w30 for the chaincase.. yahoo.. bad thing is i didn't started the hydro pumps. and lines yet..
Yes, the wear ring and wear sleeve is the same.
Wow, i'd never suspect one chain to wear like that and the others all be ok. All 4 run in the oil bath, so you'd expect them to all be in the same state.
Glad you found the needed bearings.
When you install the gear reduction boxes, make sure you adjust its location to have equal slack on the front and rear chains.You should be able to slide it forward and back.
Also, as you opened up the drive motors, make sure you put thread locker on the threads of the 4 long bolts, not the 4 bounting bolts to the reduction box. This will prevent it leaking oil back along the threads and out of the heads of the bolts. It won't flow, but it 'can' weep out of here if the threads are not sealed.
 

skidsteer.ca

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Yes, the wear ring and wear sleeve is the same.
Wow, i'd never suspect one chain to wear like that and the others all be ok. All 4 run in the oil bath, so you'd expect them to all be in the same state.
Glad you found the needed bearings.
When you install the gear reduction boxes, make sure you adjust its location to have equal slack on the front and rear chains.You should be able to slide it forward and back.
Also, as you opened up the drive motors, make sure you put thread locker on the threads of the 4 long bolts, not the 4 bounting bolts to the reduction box. This will prevent it leaking oil back along the threads and out of the heads of the bolts. It won't flow, but it 'can' weep out of here if the threads are not sealed.
Wonder if one chain was replaced with a cheap one, or maybey it got 3 new ones at some point. Must be a reason.
Ken
 
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bluthunder

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Wonder if one chain was replaced with a cheap one, or maybey it got 3 new ones at some point. Must be a reason.
Ken
UPDATE... I brought the chain to a machine shop and have it machined so that i could easily detached the worn out chain when i can buy a new one.. Thanks Tazz I'll look in to it regarding the thread locker.. Found some new headache. all of my axle housing are worn out.. so all of the seal i bought aren't gonna do a good job so i'll be replacing it tomorrow... one of the housing looks like a prob because the upper side is deformed/ worn out so i will need to refit different kinds of seals so that i won't have to do a lot off machining.. all of the wear sleeves are worn out.. some are tight some are lose like 3mm. gap... since i don't have time for machining.. all of the housing will have different sizes for the oils seal inside diameter and outside diameter.. worse of all.. wear sleeves are welded... damn.. all of the job i made are getting bigger and bigger.. endless scenarios.. i got a deadline next week and steel haven't done a thing with the hydraulic lines/ pumps yet...
 

OldMachinist

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Just got back from the shop. I've check the chains and manage to undo three because it has a lock pin so it's easy to break the chain. Can anyone tell me the the length of the chains per wheel. Cause one of the chains that I have is slightly longer than the other one. both are from the rear axles. I got a gear whose teeth are worn out. the one's sticking out from the reduction gears driving the chains. Axle Bearings are: LM 104949 - Bearing LM 104912 - Cup Reduction Gear Bearings are: LM 501349 - bearing LM 501310 - cup LM 506849 - Bearing LM 506810 - cup Just canvassed it this morning looks like i'm gonna have a hard time getting these.. Manage to get a timken LM506849 - set but no luck with the LM 501349. as for the axle bearings there are only 2 sets left (timken). Looks like i have to get them all, before it runs out. gonna buy them tomorrow. I also got the drive motors unassemble.. its really dirty.. found some plastics inside and i don't know where they came from.. gonna replace all the o-rings. good thing there's no sign of wornouts and scratches. by the way anyone has a drive motor manuals for the 743? really appreciate it if someone i can download it.
Here's a link to the complete hydrostatic motor repair manual. It covers models prior to 1999.
http://www.mediafire.com/file/vqlqjzmwmtv/Motor_component_repair_manual.pdf
 
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bluthunder

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Thanks OLDMachinist.. This will really help....
guys.. update..
finished lapping of hydrostatic motor and hydraulic pump vickers. already installed chaincase with ease. no more leaks from the chaincase anymore.. also started draining the old oil.. boy i already used up 3 pails of hydraulic oil.. hmmm. looks like i still have air in the system. there's also something i wanted to share. the hydrostatic pump is quite noisy. i'm not sure if its air or i have a worn out pump. sometimes the noise dies done and comes again.. any explanation guys? need help how to remove air from the pump. also tried the attachment breaker. still there's no force that i expect.. could this be the cause of air in the system? drove it around and looks like the hydro motors are working great. except for the noise from the hydrostatic pump.. what should i do guys..
 

jerry

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guys.. update..
finished lapping of hydrostatic motor and hydraulic pump vickers. already installed chaincase with ease. no more leaks from the chaincase anymore.. also started draining the old oil.. boy i already used up 3 pails of hydraulic oil.. hmmm. looks like i still have air in the system. there's also something i wanted to share. the hydrostatic pump is quite noisy. i'm not sure if its air or i have a worn out pump. sometimes the noise dies done and comes again.. any explanation guys? need help how to remove air from the pump. also tried the attachment breaker. still there's no force that i expect.. could this be the cause of air in the system? drove it around and looks like the hydro motors are working great. except for the noise from the hydrostatic pump.. what should i do guys..
Give the pump time, after I did mine it was as noisy as before, then a few days later came a time when I could not use it for a month. When I started it up again it was quiet, I think it is just air in the oil and it takes time to come out.
 

Tazza

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Give the pump time, after I did mine it was as noisy as before, then a few days later came a time when I could not use it for a month. When I started it up again it was quiet, I think it is just air in the oil and it takes time to come out.
Time is your friend. Run it for a little while, then shut it down and let the oil settle. The foamy oil in the reserve tank will settle out and you will draw in non foamy oil. It can take time, let it do its thing, it should purge all on its own.
 
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bluthunder

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Time is your friend. Run it for a little while, then shut it down and let the oil settle. The foamy oil in the reserve tank will settle out and you will draw in non foamy oil. It can take time, let it do its thing, it should purge all on its own.
thanks tazza.. i will look into it. now i got a new problem. the auxiliary hose for the breaker doesn't give a good amount of pressure. what seems to be the problem. i just took out the control valves so that we will change new o-rings. would this be help. we also notice that when we engage the hydraulic control for the auxiliary. left auxiliary has a good amount of pressure but when we engage the right auxiliary it has less amount of pressure. could the control valve be damaged?
 
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bluthunder

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thanks tazza.. i will look into it. now i got a new problem. the auxiliary hose for the breaker doesn't give a good amount of pressure. what seems to be the problem. i just took out the control valves so that we will change new o-rings. would this be help. we also notice that when we engage the hydraulic control for the auxiliary. left auxiliary has a good amount of pressure but when we engage the right auxiliary it has less amount of pressure. could the control valve be damaged?
i have a breaker attachment with a 300 psi nitrogen attachment.. thus the psi that i loaded to much for the 11gpm of my auxiliary thus causing it not to work properly?
 

Tazza

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i have a breaker attachment with a 300 psi nitrogen attachment.. thus the psi that i loaded to much for the 11gpm of my auxiliary thus causing it not to work properly?
If your left stick is giving the correct pressure the right/front aux couplers should be giving the same pressure. Its all set by the main relief valve. It shouldn't be an issue with the spool for the aux hydraulics.
As for the pressure of the gas charge in the breaker, i have no idea. I thought if the flow was lower the strikes would just not be so close together, so less impacts per minute.
 
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bluthunder

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If your left stick is giving the correct pressure the right/front aux couplers should be giving the same pressure. Its all set by the main relief valve. It shouldn't be an issue with the spool for the aux hydraulics.
As for the pressure of the gas charge in the breaker, i have no idea. I thought if the flow was lower the strikes would just not be so close together, so less impacts per minute.
so the pressure for the hydraulics is controlled by the main relief valve? whats the process in adjusting the pressure..
 

Tazza

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so the pressure for the hydraulics is controlled by the main relief valve? whats the process in adjusting the pressure..
It depends on the relief you have fitted. Some you can adjust with a screw, others you need to adjust with small shims. I can't remember off hand exactle where it is located, but look for something screwed into the housing away from your spool sections. It won't look like a standard plug like the load chacks on each segment looks like, it will be about 1.5-2" long.
Hopefully that gives you an idea of what to look for.
Your lift section will have one fitted, but this is set to about 3-5,000 PSI this is to protect the rams/hoses if your lift more than its designed for.
 

OldMachinist

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It depends on the relief you have fitted. Some you can adjust with a screw, others you need to adjust with small shims. I can't remember off hand exactle where it is located, but look for something screwed into the housing away from your spool sections. It won't look like a standard plug like the load chacks on each segment looks like, it will be about 1.5-2" long.
Hopefully that gives you an idea of what to look for.
Your lift section will have one fitted, but this is set to about 3-5,000 PSI this is to protect the rams/hoses if your lift more than its designed for.
Serial number 14999 and below uses shims and 15001 and above is adjustable by turning adjustment screw.
 
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bluthunder

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Serial number 14999 and below uses shims and 15001 and above is adjustable by turning adjustment screw.
Thanks Old and Tazza. found the main relief valve. turns out you can adjust it by turning the screw. I bought this morning a 5000 psi gauge and i actually connected it with the auxillary section and engaged it.. guess what. i was just pumping aroung 1500 PSI. how much psi shoud a 15001 above BOBCAT 743 giving off at the auxiliary line. Is 2250-2400 psi the correct pressure?
 

Tazza

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Thanks Old and Tazza. found the main relief valve. turns out you can adjust it by turning the screw. I bought this morning a 5000 psi gauge and i actually connected it with the auxillary section and engaged it.. guess what. i was just pumping aroung 1500 PSI. how much psi shoud a 15001 above BOBCAT 743 giving off at the auxiliary line. Is 2250-2400 psi the correct pressure?
It should be around 2,500'ish i can't remember the exact figure, but its around that. 1,500 is rather low.
 
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bluthunder

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Yes 2250 to 2400psi at the quick couplers is correct by the service manual.
guys guess what found another prob. im gonna check the charge pressure line. when i engage the auxiliary detent both tubes give pressure which not the right thing to be happening. looks like i have a problem with the controlve valve or there is a build up pressure on my return lines. need help again.
 

Tazza

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guys guess what found another prob. im gonna check the charge pressure line. when i engage the auxiliary detent both tubes give pressure which not the right thing to be happening. looks like i have a problem with the controlve valve or there is a build up pressure on my return lines. need help again.
Just how much pressure is in the other line? I think its normal for there to be a little flow, but not a jet across the shed.
 
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bluthunder

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Just how much pressure is in the other line? I think its normal for there to be a little flow, but not a jet across the shed.
gonna check whether its the same pressure.. but my mechanics told me that the flow wouldn't budge because of the other line. it should be less. nut unless i have a bad control valve. or my charge pressure is high
 

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