RTV: 4 wheel drive L, M or H? Diff Lock.

[Hd883chopper]

2010 RTV900
3 cyl diesel 4x4
875 hrs

Good Evening,

I was hoping to get some advice from the experienced RTV owners out there. Machines are different so I wanted to ask. On the RTV900, if I shift into 4wd, power goes to what wheels? I only ask because there is a Diff Lock lever that I can throw and I would think that engages at least one other wheel. Can someone tell me what wheels are engaged with just 4x4 and what happens in addition when using the Diff Lock?

Also, when operating the RTV 900 in 4wd, should I only be in Low? Does it make a difference if the Diff Lock is engaged?

I'm asking because of my experience with another side x side of mine which is a Honda Pioneer. I was told by the dealer that if I locked the differential, I should be in low gear and no more than crawling, think 5mph or less. But I could run all day in 4x4 (without locking the diff) and not worry about speed. So how do you all handle 4x4 on the RTV? What gear and if you do you use the Diff Lock, does that change your speed or action?

Thx,
HD

 

[GeoHorn]

In 4WD all four wheel receive power. The diff lock will lock the rear wheels together only.... no differential action will occur... both rear wheels will turn exactly same RPM. You can use Diff Lock in any gear, but only apply it when wheels are turning very slowly.... and only on turf, never pavement.

 

[85Hokie]

HD,

lets talk about 4wd ....... that in itself is somewhat misleading. WHILE absolutly true that ALL FOUR wheel can drive - they do NOT drive all the time while in 4WD!!! OK - that sounds crazy but true.

Lets start with the basics - if a tractor is in 2WD and gets in a position that one rear wheel is slightly above the ground - that non friction wheel will spin and the other side will NOT - and to add a little bit to the puzzle, that spinning wheel is SPINNING twice as fast as it would be normally due to the other side NOT spinning at all!

Now... lets put it in 4WD - now power to placed EQUALLY to the front and rear diffys - so NOW 4 wheels have the potential to drive ...... but again the same problem holds true. WHEN placed on a bump where the right front and left rear tires are in the air or have very little grip - BOTH will spin and the other sides of the same axles will not spin!!! Again the spinning is twice as fast as normal.

Now the best part of the equation is the differential lock - this basically forces the rear axle to become locked in place - BOTH rear tires are going to spin at the same rate - regardless of the terrain.
Since the rears are locked - and if on a ground that can provide traction - the tractor is forced in a straight line, steering becomes almost impossible!

Now add the 4WD with the front engaged - well, here is the bad news - UNLESS there is a diffy lock on the front axle, the less gripped wheel up front will still SPIN!

So the moral of the story is this - in a perfect world, you have 3 wheel drive whenever you need it - DESPITE the fact that ALL FOUR WHEEL have power to them while in 4WD!!!

There are tractors - larger ones that do and can lock ALL axles together - all four wheels will turn at the same rate - and straight you will head!!!

Modern cars "see" a wheel spinning...... then the computer clamps down the brakes on that wheel , forcing the other side to grip - Subaru has one of the best 4 wheel drive systems on the planet, and does not use a differential lock, rather a computerized wheel lock.

Engage the diffy lock while either sitting still, or engaging the wheels sliiiightly - think about a pin having to find the hole to lock the system up - thus a sloooow engagement of the pin. NOW once out of slipping and sliding - MAKE sure you take the diffy lock out!! Sometimes the pin will stay in the locked position and must be pulled back out.

4WD can be used in any speed - but think about this, it should ONLY be used on a surface that will allow a little slippage - never on a hard firm surface.

 

[imnukensc]

Just in case you don't have the operator's manual for your RTV, you can read it/download it here: https://www.gartontractor.com/post/2017/05/19/kubota-rtv900-operators-manual
It has a section on how/when to use the diff lock. Doesn't answer all your questions, but is good info. 85Hokie gave an excellent explanation.

 

[Hd883chopper]

HD,

lets talk about 4wd ....... that in itself is somewhat misleading. WHILE absolutely true that ALL FOUR wheel can drive - they do NOT drive all the time while in 4WD!!! OK - that sounds crazy but true.

Thanks Hokie for that write up and that does indeed make sense for operation. Great explanation

 

[GeoHorn]

HD,

lets talk about 4wd ....... that in itself is somewhat misleading.
...
Modern cars "see" a wheel spinning...... then the computer clamps down the brakes on that wheel , forcing the other side to grip - Subaru has one of the best 4 wheel drive systems on the planet, and does not use a differential lock, rather a computerized wheel lock.
...

(This is a tongue-in-cheek response).... Since we’re being more “accurate” in our description... In actual Fact: when the brakes are applied to the wheel that is spinning.... that braked-reduction in speed forces the power-applied to transfer to the opposite wheel.... but it does NOT force the other side to “grip”. It only sends additional power to that opposite wheel. Heh-Heh...

Excellent Reality-Check, Hokie.