Dear All, I am a new member, & first of all I hope that the members of the community of this forum are all well ; We recently sold a SANY wheel loader syl956h5 for one of our customers, if my memory do not betray me I think delivery date was on 31/ 03/2021 the loader that is has a lot of friction brake pad problems and usually the caliper assy with it too , indeed the latter wear out quickly, like every 3 months sometimes less, So I would like to know all the possible root causes according to your experience which can lead to this situation ? so that I can study each case ; If this already happened to you what can I do to to solve this problem or at least reduce the frequency of breakdowns ?
As bad as I hate to say it, I'd bet my life it's the quality of the materials in the rotors and brake pads.
It's hard to find any information or photos of the interior of the operator's cab. Does the braking system of this particular model of loader have one brake pedal or two.?
Thanks for your answer , Yes, I suspected the same thing ,but do you have any idea what can I do ? should I for exemple see with a lathe operator to make me a brake rotors with better quality materials ? or is there any risk for this solution ?, as for the brake pads I just found out that there is an the equivalent in CAT thus better quality materials. but for the caliper assy I still dont understand why we lose the seals as you can see in this image
Thank for your help sir ; The braking system of this loader have only one brake pedal , but I'm curious why is the number of brake pedals important to explain this situation ? You shalls find the pictures that u asked me for. Summary of the problem : -The caliper assy lose the seals very quickly - The brake pads wear very quickly - Till now we never had a brake rotary problem but we fear we can have at any moment
More pictures data of the matter
Well, for some reason I can't get the thumbnail pics to enlarge.
I had to log out and back in, now the pics enlarge Can you post some pics of the brake assembly assembled on the axle? Those look like shoes and not pads.
what about picture from the part book ?
I got it working now. I would rather you post them here so others can see what's going on. A parts book breakdown pic would help.......I think.
Hi , Here is the brake system detail according to the Book
Other Picture for the axle
No idea of the model year but most manufacturers quit using external dry disk brakes in wheel loaders back in the early 2000 time frame. They just don't handle dirt and debris well. There have been several threads discussing the quality of parts and machines built in China as well. Where have you been getting your parts from for this machine?
If this machine uses the service brakes also for the park brake, maybe the park brake function is not releasing properly
- The the Model year is 2020 -How does dirt and debris affect dry disk brakes ? - The problem is the Brake disks are ok , it is the caliper assy and the brake pad that have problem (parts on the picture uploaded ) - We have been getting our parts from china.
They are separated the park brake is ok
The reason I asked about the number of brake pedals is that most modern wheel loaders have two brake pedals. See the illustration below. The pedal on the right operates only the brakes , the one on the left operates the brakes but also disconnects the transmission drive. When the operator is dumping the bucket he uses the left pedal and as a result the machine is not pushing against the transmission so the hydraulics work faster. I've seen cases of brake wear on machines of that design where the operator was (incorrectly) using the right pedal for braking during dumping. I wanted to eliminate potentially incorrect operation as a factor in the brake wear problem. Another reason that made me ask about the number of brake pedals was that you mentioned frequent failures of the seals in the calipers. That to me indicated heat, and also suggested the possibility of incorrect operation.
Because of the exposed nature of the brakes, any dirt & fine debris can enter the space between the pad and disc, acting like grinding compound and wearing away both the friction material of the brake pads and also the braking surface of the dry disk. This is especially true if there is even a hint of moisture around the brakes.
Is it just dust seal failure, or is the caliper actually leaking?
Not dust seal failure , we always find that the caliper is leaking
I See Thank You Very Much
I Understand Thanks a lot
But for only one pedal is it still safe to say that maybe it is maybe an incorect operation ? after all what could make the caliper assy overheating ?
I agree. I can think of the following possibilities:- 1. Operating with one foot resting on the brake pedal - therefore the brakes will always be partially applied and so continually generating heat. 2. An accumulation of dirt under the rear side of the brake pedal, thereby not permitting it to fully return to the OFF position. Again down to the operator for not keeping his cab clean and tidy. 3. An accumulation of dirt and debris around the brake calipers that could cause seizure of the caliper pistons which would also result in the brakes being partially "applied". It would be interesting if you could get some photos of the brake caliper/disc area a few days of operation after a repair. That ought to give an indication of the levels of dirt/debris contamination in the area around the brakes.
I think im througly confused. We are seeing pictures of a brake caliper, along with a brake shoe instead of pad.....the two cannot go together. Am i missing something??
Thanks a lot these possibilities are very helpfiul and did gave new clues to study
My Bad here are the pictures of the pads
I dont remember seeing hours on the unit? Hours between total brake wear out? Are the calipers leaking from overextended pistons because the pads weren't replaced before service limit was reached? Is it all four corners, one axle, or just one corner? What job does loader have, quarry, truck loading, street running, lots of hills?
We have Deere H, J, and K 544 machines, and do municipal size sewer projects. They are equipped with wet brakes (in the axle). It takes less than 1000 hours to destroy the brakes, in my application, without axle coolers. We've since added the optional axle oil coolers. Without knowing any of the particulars, dry brakes in my applications would definitely run way too hot and wear out way too early. Repeated 20mph to zero stops, over a 8hr shift, generates a tremendous amount of heat just from the brakes.
Ok thank you for your questions : For the latest machine that had such a problem all 4 brakes wear out at 2261 for the first time. How does " quarry, truck loading, street running, lots of hills" affect the machine for each case ? because the loaders they all have this problem but the frequency is quite different
I surely Totaly agree with u
If all the loaders have basically the same brake wear problems and only the frequency between brake failures changes from one machine to the next then I would say that first & foremost you are up against a design problem - the dry disc brakes are simply not up to the task of stopping the loader for an extended period of time without high rates of wear on the pad friction material and the discs. As HNC pointed out dry brakes went out of fashion on loaders of this size maybe 15+ years ago. If Cat pads will fit I would guess that Sany has probably copied the brake design from a C-Series Cat loader of the 1980’s. The only way I can see to mitigate the problem is to carefully study the operations using these loaders that have the fewest number of brake problems in order to determine what they are “doing right” and try to duplicate those operational practices at the customers who are experiencing the most brake problems. This will not cure the issue though, only mitigate it. I think that you will be battling this brake wear problem as long as the loaders are in operation.
One of the things you may want to look into if you are repeatedly changing friction discs is better lining material. The industry has moved to paper linings which don't handle heat well. Your 20mph-0 stops will generate a lot of it! Some companies will put bronze in place of paper in problem applications, but in "wet brakes" bronze has a lower coeff of friction. You might want to look into Braketex (Kevlar Composite) which has a higher coeff and much more heat resistance than paper.
Incorrectly using the de-clutch/brake pedal can cause problems also, if going downhill and use the declutch pedal instead of the brake pedal the trans & engine are no longer providing any braking and can eat brakes QUICK
But if you look at the photo in Post #5 on Page 1 it appears as though the loader is only equipped with one brake pedal, unless it has a hand-operated throttle that is….. I’d like to get hold of an operator’s manual and see what it says regarding how to use the brakes. My suspicion is that the service brake system is quite simply waaaay under-designed considering the size of the machine.
Out of curiosity I searched the internet for, and managed to download, a copy of the operator manual. In summary: - 1. Only one service brake pedal. 2. No transmission disconnect/de-clutch system coupled to the brakes, so all the time the machine is trying to drive against them. 3. No recommendations regarding downshifting the transmission to reduce the load on the braking system. Pretty much what I suspected above. A poorly-designed, cheap system that has not been used in machines produced by more "advanced" OEMs for well over 20 years. Add in the possibility of poorly-trained operators it is easy to see why the brake pads don't last long.
the pads and caliper look like some I have seen before wagner lockeed don't know if they would be interchangeable
I'm confused. There's a pic of a caliper, then this. That sure looks like a drum brake shoe, not a disc pad.
The OP did correct himself later and post photos of worn-out pads. See Post #27 above.