Changing front axle lube

[kupperpooh]

When changing the front axle lube on my boomer 30 i see 3 drain plugs, 1 in the center and 1 on each outer hub assembly. the book says it take 1.24 gallons. so after draining all 3 do i just put the 1.24 gallons on the middle fill cap?

 

[rScotty]

When changing the front axle lube on my boomer 30 i see 3 drain plugs, 1 in the center and 1 on each outer hub assembly. the book says it take 1.24 gallons. so after draining all 3 do i just put the 1.24 gallons on the middle fill cap?

That sounds like the bevel gear drive front axle that Yanmar invented back in the 1970s. Maybe if we discuss the design that will help answer questions. Yanmar's patent ran its course - as patents are designed to do - and today everyone uses that front end pretty much just as it was originally designed. Even Yanmar's arch rivals use that same axle today and with very little or no change. And for good reason, it's excellent.
But at the time, going with that new axle was a big gamble by Yanmar. It was hugely complex and expensive compared to the simple but troublesome variations on U-joints that had been traditionally used for getting drive to the steering wheels. U joints work just barely good enough to be OK for US dryland farming, but they are a real hassle where much of the farming is in wet rice paddys.

As designed, changing the oil on that front drive axle is not an instant process. Sure enough, there are 3 drains - one for the center and one for each end. And you add oil only to the middle section - just as you figured. The way a front end oil change is usually done is that all are drained, replugged, and then slightly overfilling the the center section allows oil to migrate (slowly) through the outer bevel gear bearings and into the end sections. Then you check oil level in a day or so and then adjust the oil level in the center section up to the center line of the axle you can see directly inside the fill hole. if no dipstick to help, use a straw & flashlight and feel around. This can take a few days, but the axle isn't very sensitive to oil level as long as there is some, and failures are few.

One reason it was made that way was as the inventors of the axle saw it, the big danger to their very $$ expensive fancy multiple bearing and bevel gear axle would be water - think of rice paddys again. So they made the axle geometry inside the casting such that any water would migrate to the lowest place out in at the axle ends where it could be drained off and more oil added to the center section. And then they spent a lot of thought on how to seal out the water in the first place. This was very successful, and the axles don't seem to suffer much from working wet.
But they still have those multiple drains at the low points just in case.
enjoy,
rScotty

 

[747driver]

You should have a fill plug thats on top of the axle. There should be a drain plug on the side of the axle lower than the fill plug. So when you fill the axle at the top fill plug it will drain out of the drain hole showing you are full. Don't over tighten the plugs as most plugs have a crush type washer to act as a seal. Look at the washers and make sure they are not smashed.

 

[rScotty]

I think it's worth noting that 747driver just said exactly what I said....but he only had to use about a tenth of the words to do so.
rScotty

 

[747driver]

I think it's worth noting that 747driver just said exactly what I said....but he only had to use about a tenth of the words to do so.
rScotty

I just done my axle oil change !! This is what I have on my Kioti ....maybe his Boomer is different ? I know what you mean....sometimes we start typing and it leads to a novel !!!!

 

[chim]

The Boomer 30 design appears to have 3 separate oil reservoirs: The main axle tube and two final reduction gear assemblies.

Simple check would be to leave one of the final reduction drain plugs out and start filling the main axle tube. My bet is you can fill the tube and not have oil come out of the drains on the final gear assemblies.

 

[rScotty]

The Boomer 30 design appears to have 3 separate oil reservoirs: The main axle tube and two final reduction gear assemblies.

Simple check would be to leave one of the final reduction drain plugs out and start filling the main axle tube. My bet is you can fill the tube and not have oil come out of the drains on the final gear assemblies.

Yes, the Boomer design may be different for any number of reasons. The original design also appeared to have 3 separate reservoirs when I first saw it. But that was sort of deceptive. The connection between the chambers was not very obvious even on the drawings. But it existed - at least in the original - within the bearings that support the outer ends of the axle where the axle enters the bevel gear assembly. Those bearings were deliberately specified as an open-sided type of bearing rather than a shielded or sealed bearing. That allowed oil & air to flow through them - although slowly, which led to separate to the 3 separate drains.

All this came about because one of the early problems with that axle design was venting the outer hubs (which can run hotter than the center) so that they wouldn't suck in water due to temperature change when suddenly dunked. The fix was to connect all three chambers - making for a larger plenum space - and then run a vent tube up from the center pivot.
rScotty