his1911
Active Member
Where do y'all source your charging kits from, can't really justify the $1200+ that CAT wants for one, but then again we've been waiting on their field service to get out for almost a week!
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nitrogen charging kit?
- Thread starter his1911
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Nige
Senior Member
I don't know of anywhere else that does them, unless you want to buy in bits & bobs from all sorts of different suppliers. Buy a kit and look after it, it will probably last 10 or more years.
kshansen
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Very true! We still use the one we bought back in the early 1970's to service our 988 Cats with the accumulator for the hydraulic brakes. Had to add a couple valves and hoses when we needed to charge the suspension cylinders on the first 769 haul trucks.
How much does the dealer get for a service call? What is the down time on your machine costing you? Seems to me that three or four uses and you will have the tool paid for, after that it's profit!
Proper tools like a good mechanic is NOT a cost but an investment that pays for itself many times over.
his1911
Active Member
I used to work for a CAT dealer, now I'm working for a private company, I really enjoy the fact that my work environment is much more family friendly than the schedule I used to have to keep, but they do lack several more sophisticated and advanced tools, so it's kinda a toss up sometimes, which tool do I need and need more often.
If I need to charge another accumulator within the next 90 days we'll break down and buy a dealer one, if not I'll try to hold off until we get the new service truck finished up, I've way out grown an 11foot f550 .
If I need to charge another accumulator within the next 90 days we'll break down and buy a dealer one, if not I'll try to hold off until we get the new service truck finished up, I've way out grown an 11foot f550 .
John C.
Senior Member
I built one a bunch of years back and it cost a little over half the dealer price. The first item is the regulator. Mine could regulate up to 750 PSI and cost somewhere around $250. If you get good gas control valves you don't necessarily need the regulator. It is easier to hook the regulator in the bottle though. The adapters are next. There are two sizes but you use the smaller size the most. As far as I know there is only one manufacturer of those nitrogen fittings no matter who has their name on the box. I got mine through a company called Spencer Aircraft. You need at least one heavy duty needle valve and I used to use two of them. The hoses or tubes you get have to be gas rated so I had the fancy plastic ones that are a pain at times to wind up for storage. If you are charging struts on trucks you need a Y fitting as both struts should be filled at the same time.
I hooked the regulator to the bottle and then a short hose and the needle valve next. The outlet hose from that went to a Y fitting if needed and then onto the adapter fittings and on to the struts or accumulator. Using the tool is pretty straight forward for accumulators and a little more complicated for struts. Once you have used it successfully it is simple from there on out. It was good money because charging an accumulator only takes minutes with little labor involved. Charging struts could be more of a problem because the customers never got the boxes cleaned out. Carry back in the box would cause the truck to lean and the customers usually had to have it explained why. Breakers and such were pure gravy.
If you are only doing your own stuff and you only have a few pieces, it is my experience that buying the manufacturer's product doesn't pay. It happens that way because parts and pieces get lost, stolen or incorporated into something else and you have to keep going back to buy more pieces. However if you have something like a cone crusher with all those bottles around the sides the thing will pay for itself in a month. If you have an independent wrench around your area, try convincing him to buy the unit and blow blue sky at him about how much income he will get from the unit.
Good Luck!
I hooked the regulator to the bottle and then a short hose and the needle valve next. The outlet hose from that went to a Y fitting if needed and then onto the adapter fittings and on to the struts or accumulator. Using the tool is pretty straight forward for accumulators and a little more complicated for struts. Once you have used it successfully it is simple from there on out. It was good money because charging an accumulator only takes minutes with little labor involved. Charging struts could be more of a problem because the customers never got the boxes cleaned out. Carry back in the box would cause the truck to lean and the customers usually had to have it explained why. Breakers and such were pure gravy.
If you are only doing your own stuff and you only have a few pieces, it is my experience that buying the manufacturer's product doesn't pay. It happens that way because parts and pieces get lost, stolen or incorporated into something else and you have to keep going back to buy more pieces. However if you have something like a cone crusher with all those bottles around the sides the thing will pay for itself in a month. If you have an independent wrench around your area, try convincing him to buy the unit and blow blue sky at him about how much income he will get from the unit.
Good Luck!
his1911
Active Member
I've seen charge kits at Grainger, I know Bosch makes one, I'm just not sure if they're the same set up as the hvy eqpt ones? Some of those are in the $500 range which is much more palatable.
kshansen
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If you are familiar with the process and the kit has a regulator that can handle the approx. 2,000 psi in a full nitrogen cylinder I don't see a problem using the Grainers kit. Some of our set is made up of simple single wire Aeroquip -04 hose and a couple good needle valves and such. Most of what you will be doing is under 1,000 psi and nitrogen is not flammable or an problem like oxygen can be.
tctractors
Senior Member
I have a Bosch (Hydac 28x1.5) valve plus both the early and late style CAT valves, you dont need a bottle regulater as you can juggle the bottle valve its not hard to do and like most things the more you do the easier it becomes, on the Dumper Struts you can do 1 leg at a time with the Dumper parked on flat ground and a tape measure, its easier than the 2 line job for me, on un-known kit that I dont know the gas charge requirement I check the hydraulic pressure first then charge (Gas up) to 90% of the hydraulic pressure like on brake systems etc, this sort of work for me comes in slow but I often find that once a Co has me in to do 1 cylinder they have me do all that are handy to the site, allowing me to make a few ££ to cover the tooling, in the U.K. its easy to hire a N Bottle for a few days off a gas supply C'o as I cannot justify the bottle cost on an annual rent due to the low demand for this work.
tctractors
tctractors
Nige
Senior Member
Tony, Do you put 1/2" or 1" of oil in dumper struts..? We've found they work better with 1" of oil.
Also we've found a consistent method of charging that takes the tape measure (and things like seal friction) totally out of the game. First oil up the strut as normal, then give it a whiff of gas, maybe about 100psi, from the nitrogen bottle, then with gas in the strut jack the truck up until the strut tops out. Set the gas pressure to 260 +/- 5psi front or 160 +/-5psi rear with the strut extended. Drop it back onto its feet again. We had loads of grief with trucks that had on-board payload measurement systems not weighing accurately and this was what we came up with as the most consistent way of charging them.
Also we've found a consistent method of charging that takes the tape measure (and things like seal friction) totally out of the game. First oil up the strut as normal, then give it a whiff of gas, maybe about 100psi, from the nitrogen bottle, then with gas in the strut jack the truck up until the strut tops out. Set the gas pressure to 260 +/- 5psi front or 160 +/-5psi rear with the strut extended. Drop it back onto its feet again. We had loads of grief with trucks that had on-board payload measurement systems not weighing accurately and this was what we came up with as the most consistent way of charging them.
his1911
Active Member
I don't know why I didn't think about looking on Ebay.? Oh well I'll blame it on the fact that I've been busy busy busy!
Thanks for the comments guys, I've had my basic question answered and learned a few things!
Thanks for the comments guys, I've had my basic question answered and learned a few things!
kshansen
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Nige,
Do you think this would work the same for our "little" trucks, 769 C+D and a 773G?
I know I have had problems getting the heights right using the "Cat Approved" methods. Might look good when they leave the shop but next time I see them they are either too high or low on one side. I know you have to come to a nice smooth stop in a straight line or all bets are off!
Nige
Senior Member
The pressures should work for any size of Cat Truck from 769 upwards. The procedure (SEHS9411) for charging struts the way we do is in SIS but only allegedly covers 785 upwards. I see no reason to doubt that it would work on a smaller truck. If the truck has a payload measurement system installed then the easiest way to measure suspension pressures is hook the laptop up to the TPMS and look at the strut pressure. The electronic sensor in the strut will be far more accurate than any pressure gauge installed on a nitrogen charging kit, even a brand new one.
Make sure you put a good quantity of oil in the strut. I usually oil them up to 1-1/2" (manual says 1"), then go and have lunch. Come back and drain them down to 1" - most of what comes out will be air that was trapped in the oil when it was pumped into the strut. That gets your oil level/quantity correct.
Remember that the front struts will always ride at different heights (LH lower than RH) because of the weight of the cab, despite the fact that both of them might have an identical oil & gas charge..
Make sure you put a good quantity of oil in the strut. I usually oil them up to 1-1/2" (manual says 1"), then go and have lunch. Come back and drain them down to 1" - most of what comes out will be air that was trapped in the oil when it was pumped into the strut. That gets your oil level/quantity correct.
Remember that the front struts will always ride at different heights (LH lower than RH) because of the weight of the cab, despite the fact that both of them might have an identical oil & gas charge..
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tctractors
Senior Member
How are things Nige, good bit of script there on the truck strut beano, this would not be a thing I would get much chance to follow through on as my sort of customers just want the truck to look level, on the oil fill thing if I have had the strut out I do the oil fill task with the strut ley down on the floor, this is more of a pour in thing so not much froth?? then its (For Me) out with the tape measure to set the ride hight, with a return re-gas happening about 4 months later, as the strut re-seal can be costly due to gas burns and the truck heading for a new owner after a job finish???
My biggest use of N/Charge stuff is on demo hammers and largish loading shovels that sprout those Bosch cans like apples on a Tree often having 6 to 10 smallish spheres plus a largish 1 for the soft ride on the loader frame, I can soon majic up some coins puffing these up but its still hard to get the tooling cost back in the Bank , so its best to build up a kit as and when practical, the CAT "New Style" valve is an old style job Terex used an age ago, this valve is not expensive, the gauges are cheap items the needle valves (taps) ??? and the regulator is not realy needed, think of the coins you can save by being gentle on the bottle tap.
tctractors
My biggest use of N/Charge stuff is on demo hammers and largish loading shovels that sprout those Bosch cans like apples on a Tree often having 6 to 10 smallish spheres plus a largish 1 for the soft ride on the loader frame, I can soon majic up some coins puffing these up but its still hard to get the tooling cost back in the Bank , so its best to build up a kit as and when practical, the CAT "New Style" valve is an old style job Terex used an age ago, this valve is not expensive, the gauges are cheap items the needle valves (taps) ??? and the regulator is not realy needed, think of the coins you can save by being gentle on the bottle tap.
tctractors
kshansen
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I'll make a note of this and give it a try next time I do one of these. I do like the idea of over filling and letting it set then draw off the air and foam.
Nige
Senior Member
The 1" oil level is critical to getting both the truck to sit right and also to get the required level of accuracy of an on-board payload system (if you have one installed). Also the quantity of oil in the strut affects damping so long-term you're going to experience frame twisting and cracking if your suspension struts are not correctly damped. I've seen enough haul truck chassis fallen in half before thank you very much...........
Doesn't matter how you fill it (unless the strut is being overhauled and you simply pour it into the cylinder before installing the rod) the oil will aerate as you force it into the strut from outside. Because the struts use 10W oil we hook a hydraulic test line up to the steering system test port and plumb it into the manifold for the nitrogen charging kit. That way we can use the machine itself to oil up the struts. If we are doing a simple "discharge & recharge" procedure then to oil up the 2 struts on each end of a 793 with the engine at idle speed takes about 2 minutes. Note to self: - Remember to top up the steering tank afterwards .......
Doesn't matter how you fill it (unless the strut is being overhauled and you simply pour it into the cylinder before installing the rod) the oil will aerate as you force it into the strut from outside. Because the struts use 10W oil we hook a hydraulic test line up to the steering system test port and plumb it into the manifold for the nitrogen charging kit. That way we can use the machine itself to oil up the struts. If we are doing a simple "discharge & recharge" procedure then to oil up the 2 struts on each end of a 793 with the engine at idle speed takes about 2 minutes. Note to self: - Remember to top up the steering tank afterwards .......
kshansen
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Because the struts use 10W oil we hook a hydraulic test line up to the steering system test port and plumb it into the manifold for the nitrogen charging kit. That way we can use the machine itself to oil up the struts. If we are doing a simple "discharge & recharge" procedure then to oil up the 2 struts on each end of a 793 with the engine at idle speed takes about 2 minutes. Note to self: - Remember to top up the steering tank afterwards .......
Another simple and brilliant idea from Nige. All these years I have been pumping the oil in with the hand pump while that steering pump is sitting there doing nothing!:Banghead
I tried using the air pump from our bulk tank system but it was just a little to low on pressure to do the job.
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Nige
Senior Member
You conveniently forget to mention that the "simple and brilliant idea" also saves you from the need to buy a 9U-5617 Oil Pump Group @ $7000+ to charge oil into suspensions and which takes about 1 hour for each strut rather than having the capability to do 2 struts in 2 minutes.
Here's what our kit looks like. It's a bit of a Christmas tree of fittings but it does the job and more importantly means we can oil & gas struts without having to disconnect or change any fittings. The fitting on the LH is for nitrogen and is open, just a quick coupler to the gas line but it is isolated by the valve immediately to the right of it. A self-sealing quick coupler is installed in the tee immediately to the RH side of the nitrogen control valve and it's through that coupling that the hydraulic oil is supplied with the valve on the LH side of it remaining closed during the process. Once the struts are oiled up the engine is shut down and the test line is disconnected, thus closing that coupler. Then the nitrogen valve is opened allowing us to gas the struts.
As you can see it requires 2 transmission test lines coupled together to reach the rear struts on the machine, the front struts can be done with just one line.
Also remember that I have a fleet of 36 trucks here, all of which needs suspensions doing as a PM Checklist item every 4000 operating hours or about 7-8 months. We actually have 3 nitrogen kits in our Tool Store; one set up for truck suspensions, one set up for truck steering accumulators, and a 3rd kit for "everything else". Saves time ...........
Here's what our kit looks like. It's a bit of a Christmas tree of fittings but it does the job and more importantly means we can oil & gas struts without having to disconnect or change any fittings. The fitting on the LH is for nitrogen and is open, just a quick coupler to the gas line but it is isolated by the valve immediately to the right of it. A self-sealing quick coupler is installed in the tee immediately to the RH side of the nitrogen control valve and it's through that coupling that the hydraulic oil is supplied with the valve on the LH side of it remaining closed during the process. Once the struts are oiled up the engine is shut down and the test line is disconnected, thus closing that coupler. Then the nitrogen valve is opened allowing us to gas the struts.
As you can see it requires 2 transmission test lines coupled together to reach the rear struts on the machine, the front struts can be done with just one line.
Also remember that I have a fleet of 36 trucks here, all of which needs suspensions doing as a PM Checklist item every 4000 operating hours or about 7-8 months. We actually have 3 nitrogen kits in our Tool Store; one set up for truck suspensions, one set up for truck steering accumulators, and a 3rd kit for "everything else". Saves time ...........
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kshansen
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If I didn't know better I would think you had a picture of our set up with the three needle valves, except ours have yellow handles. I can't get my head around the work needed to keep 36 large haul trucks and all the other equipment in an operation of that size up and running. Guessing you have more than one mechanic handling the service and repair work!
Nige
Senior Member
Just a few more than one ....... we use 777F's as water trucks.I can't get my head around the work needed to keep 36 large haul trucks and all the other equipment in an operation of that size up and running. Guessing you have more than one mechanic handling the service and repair work!
Does your kit have the quick connector for the oil like my photo..?
I'm just finishing off supervising the installation of a Final Drive and brake tests on a 994F, then once it's tested I can leave it to the tyre germs who'll boot its ass out to work tonight and pull another one straight in for PM that's overdue but we couldn't take it while the one was down for the FD. That will take care of tomorrow, then I have a Hitachi 3600 excavator scheduled for replacement of 2 boom cylinders starting a 7:00AM on Monday. No rest for the wicked ...........
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