Kubota g18 PTO

[Jez456]

Hi have a trusty g18 high dump great little machine but the PTO belts fail regularly...as in around 25 - 50 hours tops.
I install them to factory spaces as per the manual but never seem to last.
They are a marched pair my mitsuboshi which I gather Kubota fit from new and are a good brand. Any ideas where I am going wrong?

Thanks in advance.

 

[Dave_eng]

Hi have a trusty g18 high dump great little machine but the PTO belts fail regularly...as in around 25 - 50 hours tops.
I install them to factory spaces as per the manual but never seem to last.
They are a marched pair my mitsuboshi which I gather Kubota fit from new and are a good brand. Any ideas where I am going wrong?

Thanks in advance.

Need particulars on the belts. Something like AP103 or BP120

When they fail what happens? Break, come off and get torn up?

Dave

 

[Jez456]

Hi Dave,

not sure on the belts here is a link to the ones i have been using...oh as i am a newbie on here i can't post links!

but they are on ebay, search Genuine-Mitsuboshi-PTO-Belts-For-Kubota-G18-G21

when the new set turn up they may have some numbers on there.

they seem to get hardened like they are burning up and end up snapping.

i will see if the old ones are still about and get some pictures. (or maybe not as i don't qualify for that either!

 

[Dave_eng]

Determining why your belts are failing is difficult from a distance. I have to assume you have checked the obvious such as a bad bearing in a blade spindle or idler pulley.

Seeing you are using a non Kubota belt from a company who claims to supply Kubota is a big unknown in terms of the belt you actually receive.

Measuring V belts is easy in order to buy at lower prices than a dealer and also ensure that you are getting a Kevlar belt..

Watch this youtube video.

https://www.youtube.com/watch?v=lIQ1-rBHG6g

First measure the outside width of your belt. In most cases an A , B or a C

Once you have measured the outside length of your V belt, I can help you find one on eBay

Lets assume you measure the length of your belt at 120".

You search on eBay or a CP120 v belt and end up with this one.

https://www.ebay.co.uk/itm/Dayco-Sup...0AAOSwN~VeM6wr

The A, B or C cross section is what you tape measure.

The letter "P" is the common designator for a Kevlar reinforced belt.

Assuming you determine the belt width to be a C and the outside length to be 120"..............

This leads to the proper belt being CP120.

While all manufacturers have their own unique part number for V belts most also follow the universal way of identifying their products. Carlisle, Dayco, Goodyear.... they all do it the same!

Dave

 

[Jez456]

Thanks for all the info there Dave...when the new ones turn up I will get the dimensions etc

Its actually the PTO belts that run from the engine crankshaft to a pulley on a propshaft to the cutting deck gearbox that is my issue not that that make a difference for you identifying a belt as per your info.

 

[Dave_eng]

Thanks for all the info there Dave...when the new ones turn up I will get the dimensions etc

Its actually the PTO belts that run from the engine crankshaft to a pulley on a propshaft to the cutting deck gearbox that is my issue not that that make a difference for you identifying a belt as per your info.

My brother had a mower (not Kubota) with a similar dual belt to jack shaft setup and was having belt issues.

When I took the time to get down where I could see the pulleys it was very apparent that he had hit and bent some of the lower pulley hardware and the belts were not all in a vertical plane. This was corrected and his belt failures stopped.

Dave

 

[Jez456]

Hi Dave, so the new mitsuboshi belts turned up i still can not attach pictures yet but written on the belts we have;

''heavy duty for reverse bend set free LB-31 03 ZB''

and the dimensions are

Inside Length Approx: 31 inch
Belt Width Approx: 16.5mm
Belt Depth Approx: 9.8mm

(they are meant to be a matched pair as run in parallel)

had a quick look on other web sites and these are meant to be high quality agricultural.

on fitting the new belts i have found a belt keeper missing, this is not to stop the belts coming off particularly, but when pto is disengaged without the keeper the belts bow out allowing the front one to pretty much rest on the muffler....clearances are rather tight at the best of times!
I am kinda thinking the front belt is getting cooked and heat damaged and failing and the other can not handle operation on its own so fails soon after.

the one old belt i have has basically snapped, not burned out by pulley wear so would assume this one was the further away from the muffler?!

cheers

jeremy.

PS ordered up the missing bit...looks like its been gone a long time, tore off on a belt failure before we had the machine i guess!

 

[lugbolt]

those belts are supposed to be a matched set. Kubota sells them as matched pair only. They're a little more expensive but they're more expensive for a reason.

are they burning up? Or do they break cleanly? Any obvious markings on the failed belts? Could you post a picture of the belts that have failed?

 

[Jez456]

Hi Lugbolt check out the pictures, I have a feeling the front most belt is getting cooked on the exhaust and causing it to fail leaving the machine on one belt (pictured) which ends up just snapping. Apart from the snap it looks in good order.
In the picture where the belts are mounted on the machine you can just make out a bolt between belt and exhaust....this is where a missing belt keeped goes which should keep the belt off the hot exhaust, that is the only thing i can see causing my issue, apart obviously from the belts but they are meant to be of high quality! I am dubious of paying 4 times as much for a genuine set if they do not last any longer! Kubota parts are quite pricey in the UK.

cheers

 

[Westydexta]

Hi have a trusty g18 high dump great little machine but the PTO belts fail regularly...as in around 25 - 50 hours tops.
I install them to factory spaces as per the manual but never seem to last.
They are a marched pair my mitsuboshi which I gather Kubota fit from new and are a good brand. Any ideas where I am going wrong?

Thanks in advance.

I had same issue with my G21 and the fault was worn pulleys. I diagnosed it by checking the new belts once fitted and one was slacker than the other. On further inspection the inner belt was sitting lower within the pulley channel than the other.

 

[lugbolt]

those belts are a matched set, in other words their width, vee angle, and length are matched to each other to within 0.25mm as I recall. When you buy them at parts store, they are not matched. They are just two belts that might be 1mm off of each other, which is not what we want.

Look closely at your pto linkage. If the belts rub anywhere, guides, pins, sheet metal belt covers, anything, they will not last. Secondly your idler/tensioner. They were known to fail, a lot of times they'd be fine at rest and after running a while they'd seize the bearing and smoke the belts.

 

[Pawel]

Hi Dave,
not sure on the belts here is a link to the ones i have been using...oh as i am a newbie on here i can't post links!
but they are on ebay, search Genuine-Mitsuboshi-PTO-Belts-For-Kubota-G18-G21
when the new set turn up they may have some numbers on there.
they seem to get hardened like they are burning up and end up snapping.
i will see if the old ones are still about and get some pictures. (or maybe not as i don't qualify for that either!

Hi Jez456,
Could you write me a part number of Mitsuboshi belt?
I use v-belts made by KRAMP, but I am looking for a better solution.
Thanks for respon

 

[TheOldHokie]

those belts are a matched set, in other words their width, vee angle, and length are matched to each other to within 0.25mm as I recall. When you buy them at parts store, they are not matched. They are just two belts that might be 1mm off of each other, which is not what we want.

You can easily buy matched belts off the shelf today. V-Belt matching standards are set by the Rubber Manufacturer's Association and only pertain to the pitch length. The process of selective fitting v-belts is onerous and there has been a lot of work done by the manufacturers to simplify this process. The variation allowed for "matched" belts is set by the RMA. It also depends on belt length and is organized into 7 different divisions. Off the shelf Gates V80, Goodyear MatchMaker, and Browning Code 1 V-belts all meet or exceed the RMA standards for matched belts. I am sure you can find similar products from other manufacturers.

Here is a simple explanation from Gates:

Gates V80 V-belt matching program (PDF)

Dan