Hi range HST bogging on grade - CK30 (CT230 actually)

[k0ua]

The idea of keeping the tractor in 4WD is when going downhill in 2WD if the surface is slippery (like gravel on the road) you can lose control of the tractor and have runaway especially if it is loaded or the loader is full of something heavy. Here is what happens, the rear wheels start to slip as the tractor wants to go downhill faster than the tires are turning, the engine is providing compression braking. Once the rears start to slip, it can get worse in a hurry, and the tractor slides down hill real quick. Wheee!

Pressing on the brakes won't help, it will only make things worse! If you can drop your bucket to help with braking that may help, or it may catch and make things worse, depending on circumstances..

The best thing to do is stay in 4WD when going down hills loaded. Now you have 4 contact patches on the road instead of 2 for compression braking to work against. While it is true there are no friction brakes on the front wheels, friction brakes are not what we are talking about here, it is the compression braking where the trouble starts.
This happened to me in a gear tractor, but I believe a Hydro tractor has enough "holdback" in Low range to do this also. Sure when you operate on a hard surface the 4WD causes tire wear on the fronts, BUT when you have a tractor runaway occur in 2WD, from lack of friction between the rear tires and the road surface, you will wish like He** you had kept it in 4WD. If you have this happen once, you will be a believer. There is a thread on here where the operator was going down a grass slope in 2WD and had the same thing happen it started to slide and he steered to miss on obstruction and overturned the tractor.

James K0UA

 

[k0ua]

I also agree HI range is for level ground, unloaded tractor for road transport, only, not for going up hills of much grade. I have a tractor that weighs as much as my pickup truck, with about 1/8 of the horsepower, I have to move it somehow, and I move it with the advantage of gearing it down, But when you put it in HI, a lot of that gear down advantage is lost and I have lost a lot of torque applied to the wheels, Of course it is going to bog down. I move up and down my hills in Med, and if it starts to bog a little, I back off of the hydro pedal and keep the engine in its powerband, as noted previously by others. When heavily loaded (not mulch but rock or gravel) I use LO.

James K0UA

 

[kiotiken]

I am doing this from my phone - what hp do you have? What is your tractor optioned with?

Remember, A lot of things come into play.

Tony

From your above mention that it is a CK30hst with 1200lb bh, loaded tires. and cab with total weight at @6500lbs, that's a load for those 30 ponies. Hopefully Tony can give you an idea of what it may be being that you said it used to do better.

Yes, that's the set up I have. I agree 30 hp isn't much when a pickup that weighs about the same can be over 300hp. I really do think it did better before and it worries me a little because the transmission's been replaced since my last road trip that seemed to go better.

 

[JonKioti]

Re: 4WD all the time.

I understand all about using it to go downhill gracefully - I rolled my lawn tractor once when it got away from me on damp grass.

However, I would think you are putting unnecessary strain on your transmission keeping it in 4WD all the time when you turn on non-slippery surfaces. At the very least, your tires will wear far more quickly.

My friend borrowed a Kubota once. I helped him pick it up, and heard the owner tell him "I keep it in 4WD all the time; it doesn't make any difference". Looking at his tires, I definitely could see the difference - far more wear than I would expect for the number of hours on his machine.

Cheers,

Jon

 

[mrutkaus]

Normal for me; when I first got the ck30hst it surprised me. After a few years of break in it got better in hi, but still only useful for level or downhill transportation or very slight grades. Don't forget to let up on the foot pedal to give the tractor more rpms, this isn't a case of the harder you push the faster it goes!

Mike

 

[Dingo Man]

I see several of you have commented that you leave 4x4 mode on all the time. This surprises me especially since I can feel the drivetrain binding when turning sharply. As with cars/trucks in 4x4 mode, it seems to me that 4x4 mode in the tractor should only be used when needed.

Am I incorrect in this understanding? Is the 4x4 mode on our tractors more like what's in my Subaru (AWD) that can be used 100% of the time with no ill effect?

I've got to agree. There is a reason these tractors are designed with engage and disengage buttons for 4x4. Like your pick up trucks you would not drive down a dry road in 4x4. It requires more power and it caused unneccessary wear and tear on your runninig gear. Take your tractors out of 4WD when not needed.

 

[Mousefield]

I've got to agree. There is a reason these tractors are designed with engage and disengage buttons for 4x4. Like your pick up trucks you would not drive down a dry road in 4x4. It requires more power and it caused unneccessary wear and tear on your runninig gear. Take your tractors out of 4WD when not needed.

:thumbsup: That's what I do, very rarely am I in 4WD.

 

[SPYDERLK]

I've got to agree. There is a reason these tractors are designed with engage and disengage buttons for 4x4. Like your pick up trucks you would not drive down a dry road in 4x4. It requires more power and it caused unneccessary wear and tear on your runninig gear. Take your tractors out of 4WD when not needed.

:thumbsup: That's what I do, very rarely am I in 4WD.

My tractor is in 4WD for about 1/2 the distance it travels for this very reason. Mine, the 7520, goes in and out easy while moving once you know the technique - and I shift it frequently according to need. Theres danger of course in not have it in gear when you need it. My Mahindra has no, or very little, front lead so really stirs up the ground in tight turns. The Kubs are much better turning because they have a lot of front lead -- lots of disturbance in 4wd when driving on the gravel drive. For tirewear and gear loading its even more important with them to choose 4wd according to occasion.
larry

 

[SPYDERLK]

Good point, it was in 4wd, but I've never taken the tractor out of 4wd, so it was the same as before. The only differences this time is the kioti cab that I've added (350 lbs I think they say) and I had pallet forks on the front which is probably an extra 50-100 lbs over the bucket.

Until I got over the grade, I couldn't get up to even mid range speed. I did come off the pedal to stop it from bogging and give it a fighting chance, moved the throttle to wide open and gently tried to pick up speed, but no go.

One more thot on mysterious power loss as conjecture since I dont know your tractor. ... My 7520 has injection timing advance for the 1st 20 minutes after a start. You can here the slight diesel rattle go away as timing retards. I was told, oddly enuf, that timing was automatically advanced for a while even after a hot start. It makes more power while the timing is advanced. I was out field dragging on hilly terrain and noticed the tractor lacking power in a section. [Its a gear tractor.] I experimented til I was sure I was getting all it had, then stopped and turned it off and re started. More Power. Went from lugging down to abusive or shifting, to coming off the top of the same hill a couple hundred rpm higher without shift. Repeatable. ... Maybe you have a similar injection setup. :confused3:
larry

 

[kiotiken]

One more thot on mysterious power loss as conjecture since I dont know your tractor. ... My 7520 has injection timing advance for the 1st 20 minutes after a start. You can here the slight diesel rattle go away as timing retards. I was told, oddly enuf, that timing was automatically advanced for a while even after a hot start. It makes more power while the timing is advanced. I was out field dragging on hilly terrain and noticed the tractor lacking power in a section. [Its a gear tractor.] I experimented til I was sure I was getting all it had, then stopped and turned it off and re started. More Power. Went from lugging down to abusive or shifting, to coming off the top of the same hill a couple hundred rpm higher without shift. Repeatable. ... Maybe you have a similar injection setup. :confused3:
larry

Well, I couldn't tell y'a. I normally wait for the tractor to warm up before moving it, but on this occasion I just needed to run next door quick to help out before we were off somewhere else for the day. I started it, waited a minute or so and then started moving in mid range. When I got off my property and onto the road, I put it in high and that's when I noticed the difference. Maybe to oil wasn't up to temp and that was part of my issue, I'm not sure, but going with your theory, the engine would already been using an injection advance and giving me the most power. I do notice more of a rattly sound when cold, but it quickly goes away after a few minutes. I've always attributed it to being cold.