Hill descent

Catch95 · Feb 9, 2005

I have a steep hill at the rear of my property. I was coming down the other day after doing some slashing. I have a small Jinma 20hp 4wd tractor, which I've had for a year. I've never had any problems on this hill but the other day it got away from me and I had one terrifying ride.

I was in 4wd, and 2nd gear in low range, with the implement on the 3PL lowered. About half way down it started to runaway. I reacted instinctively and gave it a little bit on the brakes but it just started to slide (there had been some light rain). So I concentrated on keeping it straight and hung on for the ride. Fortunately I always wear a seatbelt and have ROPS. Near the bottom the tractor "caught up" and started to slow.

I'm not sure why this time I got into trouble - but I was still shaking minutes later.

What is the best way to handle this - should I have used the diff lock, and can you engage a diff lock at speed - I guess I figured being in 4wd would be all it would need?

My long time farming neighbours said I should have been in a higher gear, but this doesn't make any sense.

Would appreciate any advice

Mark

getut · Feb 9, 2005

When you say "run away" do you mean you were sliding down the hill with the wheels either not turning at all or at least turning much slower than you were moving? or do you mean the engine compression was not enough to keep the weight slow, so the engine RPM kept climbing as the wheels turned faster?

Bob_Skurka · Feb 9, 2005

I deal with hills have had a couple wild rides myself. You should have been in a LOWER gear not a higher gear. You should stay off slopes until the grass is DRY. So those two things probably contributed to the problem. But I also wonder if part of the problem was the rotary cutter, it might have been working against you and keeping the tractor moving forward (all that depends on the sophistication of the transmission on your Jinma, which I don't know much about) but the flywheel of a rotary cutter spinning at speed, on a simple mechanical transmission, could essentially power a tractor forward when you don't want to go forward. I've seen/experienced this myself with antique gear tractors. Disengaging the PTO might have helped, but I suspect you were hanging on and the thought of attempting to disengage the PTO probably didn't enter your mind, and again, might not have helped depending on the type of transmission you have.

rbarker · Feb 9, 2005

( I was in 4wd, and 2nd gear in low range, with the implement on the 3PL lowered. About half way down it started to runaway. I reacted instinctively and gave it a little bit on the brakes but it just started to slide (there had been some light rain). So I concentrated on keeping it straight and hung on for the ride. )

Yikes! /forums/images/graemlins/shocked.gif I think you did about the only thing you could do in that situation by keeping it straight and riding it out. /forums/images/graemlins/crazy.gif Was this a real heavy impliment that "pushed" the tractor down the hill?

Glad your safe! /forums/images/graemlins/grin.gif

BTW, on my Kubota the diff lock is only supposed to be engaged from a stop. Don't know how it is on your Jinma, though.

tough451 · Feb 9, 2005

I always choose second or 3rd gear in low range on my hills I never hit the brakes unless I have too. You did well by holding a straight line.
Some times if you have alot of weight behind you and your gearing is to low it will have a similar effect as hitting the brakes is this what happened.

Henro · Feb 9, 2005

Been there, experienced that...

Chains seem to help. I kept mine on the back all year long last year due to all the rain we had.

Like Bob S said, keeping off the slopes when it is wet helps the most probably. IN my case that was not possible. Chains are no guarantee either, but using chains seems to be better than not having the chains on...

Todd_C · Feb 9, 2005

Glad your o.k. I had a similar problem last year before I got my tractor. I had a small trailer behind my ATV and loaded it with about 700-800 pounds of wood. I stared down the hill behind my house and the ATV started sliding. I was able to make it to the bottom of the hill by the skin of my teeth. I had the ATV in low range and the wheels started sliding. I opened up the throttle and held on. I decided to keep the tires turning rather than trying to control a skid. It worked but I should have known better than attempt to control 1,000 pounds with a 500lb machine. I was lucky. I have been lucky on my tractor so far. No real close calls.

johan3400 · Feb 9, 2005

I think you did a fine job just keeping it straight. I had the experience of riding a JD950 down a steep hill with a large load behind it. I believe each time we have close calls like this one we learn. Do you have Ag tires on the back or Turf? Do you have the back tires loaded or some type of weights? The wet grass adds to the risk. What would you change to be safe the next time? Maybe the next time you could lower the 3pt all the way down and that would help.

Catch95 · Feb 10, 2005

Thanks for all the posts on this.

Basically I was coming down the hill faster than the wheels were turning. I did have the PTO engaged, thinking I would mow the track on the way down - my little tractor struggles to do it on the way up.

Should I have accelerated to get the wheels to catch up - seems like the opposite of what you feel like doing?

I might put a post on the Chinese Tractor board re when you can engage the diff lock on a Jinma.

I do consider myself lucky - better than the son of a neighbour of mine who lost it on a much steeper hill, jumped (survived even with no belt or ROPS) before the tractor went off an embankment and became airborne - landing up high in a huge tree. I would have loved to have been there when he had to front his father.... Apparently they cut the tree down, the tractor came down with it, and he drove it away - something about old Fiat tractors.

Mark

Jim_Fisher · Feb 10, 2005

Catch95,

( Should I have accelerated to get the wheels to catch up - seems like the opposite of what you feel like doing? )

Good question.

You could have used a higher gear and a low engine speed as your neighbor suggested. That may well have been sufficient to prevent the incident. If you still started to slide, you could have accelerated to try to synchronize the wheel speed with the actual rate of travel.

You could have disengaged the clutch and pumped the brakes very gently to slow your descent. Since you had the tractor in four wheel drive, the front wheels would have helped to slow the tractor. Remember that if the front wheels are not turning they will have very little effect on the direction of travel.

You could also lift the three point implement enough to transfer some weight to the tractor wheels. The down side is that you would take some weight off of the steering axle. If the tractor is correctly ballasted, there shouldn't be a problem.

I think that you realize that applying the brakes when the wheels were sliding did nothing to positively affect the outcome of the situation. It's not easy to place mind over matter in an emergency situation but sometimes that is what has to be done.

Buckcreek · Feb 10, 2005

I have had The same thing happen on my little BX, When ive forgot to put it in 4 wheel drive. I have a very steep bank i have to mow, i usually go straight down it to my dads yard then take a round trip back up my drive way, and go down again, It is so steep that when the grass even has dew on it i will spin if i try to back up even with diff lock . I try to beat my dad tho this part of the property but one day i was gone and he decided to mow i seen where he had made a few passes and quit when i pulled in the drive way i got a sick feeling that somthing was wrong so i went straight to his house to check on him , and thats when i seen the two bare lines down the hill , i was doing somthing the evening before and forgot to put it back in 4wheel drive. he made the first trip down the hill and slid very fast down the hill, what scared me the most is he wont wear the seat belt, and at the bottom of the hill is a rolling ditch and when he hit it he almost went over the steering wheel , it shook him up a little and he had some bruises but he wasnt hurt seriuosly. from now on i always check to see if im in 4wheeldrive but i still cant get him to wear the seatbelt. He is getting stubborn in his old age.

rbarker · Feb 10, 2005

( Apparently they cut the tree down, the tractor came down with it, and he drove it away - something about old Fiat tractors.
)

Holy Crap! /forums/images/graemlins/shocked.gif /forums/images/graemlins/shocked.gif I would have like to have seen this! /forums/images/graemlins/grin.gif

rbarker · Feb 10, 2005

( You could have disengaged the clutch and pumped the brakes very gently to slow your descent. )

I'm not sure I agree with this. The tractor was experiencing some engine braking even though it was less effective. By disengaging the clutch the braking effect of the rolling wheels would have been lost and the tractor would have sped up more. Pumping the brakes would be much more likely to cause wheel lock and loss of control. Re-engaging the clutch after the tractor sped up would probably have caused a worsened skidding condition as well.

Maybe a throttle up would have helped match the wheel speed to the tractor's ground speed thus regaining more control over the tractor. I don't think a gear change during the wild ride would have been advisable for the same reasons.

Well, that's just my opinion anyway... /forums/images/graemlins/crazy.gif

Jim_Fisher · Feb 10, 2005

Bob,

( The tractor was experiencing some engine braking even though it was less effective. )

I can't think that the tractor was running away (as in overspeeding the engine) without losing traction since Catch95 stated that he has never experienced a problem with this hill when the surface was dry.

I suspect that the engine braking was a big part of the problem. Once traction is broken, there is no way to reduce the engine's braking effect without disengaging the clutch or increasing the engine speed to match the tractor speed. Engine braking amounts to the same thing as steady pressure on a brake pedal in slippery conditions. If you apply too much brake you will slide and you will very likely continue to slide until you let off the brake.

( Pumping the brakes would be much more likely to cause wheel lock and loss of control. )

Pumping the brakes has been the accepted practice for slowing a vehicle on a slippery surface for many years. It actually reduces the likelyhood of wheel lock. The advent of anti-lock brakes has made the practice obsolete in those vehicles so equipped.

( Re-engaging the clutch after the tractor sped up would probably have caused a worsened skidding condition as well. )

I could not agree with you more. Re-engaging the clutch would be a huge mistake.

( Maybe a throttle up would have helped match the wheel speed to the tractor's ground speed thus regaining more control over the tractor. )

That would have been my first instinct, assuming that the throttle wasn't already open. Not sure how the tractor is geared but I suspect that 2nd/low range might not have enough speed to catch up.

( I don't think a gear change during the wild ride would have been advisable for the same reasons. )

I aggree. Unless you have a synchronized transmission and a way to control engine speed with your foot shifting gears is not an option.

I went through a similar experience in a tractor trailer about twenty-five years ago. I was following a salt spreader after some freezing rain had fallen. After topping a hill, the salt spreader apparently ran out of material. I was about a half mile behind him and could see that he was still ahead of me but I couldn't see what was coming out of the back of his truck. Suddenly, the inside of the cab was very quiet. I looked at the tach and noted that the engine was idling. At the speed that I was traveling and the gear that I was in, it should have read about 1800 rpm. I applied the throttle very gently and put a very slight pressure on the trailer brakes. The driver of the truck behind me later told me that he could see my rig start to bend in the middle and then straighten out. Definitely a high pucker factor incident. /forums/images/graemlins/grin.gif

farmermatt · Feb 10, 2005

NEVER DISENGAGE THE CLUTCH WHEN GOING DOWN A STEEP HILL!! the centrigugal force of the mower wouldve been pushing you down the hill through the pto. if the wheels were spinning faster than you were moving then you shouldve disengauged pto, throttled all the way down to idle and applied a little brake pressure. diff lock wouldnt have mattered unless one wheel was spinning more than the other, but it doesnt sound like that was the case. if you did have diff lock engauged, on most tractors once you press the brakes it automatically disengages the diff lock.

matt

JerryG · Feb 10, 2005

Fellows,
If you had slid down as many hills in a truck (not a pick-up) or a tractor as I have you would know that you have two options. #1 is to out run the slide, That is to keep up gearing. Then pray that there is enough shut down area at the bottom. #2 Is to disengage the clutch and let the tires start to roll and then start applying the brakes again. If the tires are not rolling you can not stop it with the brakes nor can you control the slide.

GaryE · Feb 10, 2005

Matt,

I have to agree with Jim and Jerry, tires that are loosing traction are useless. I have spent countless hours on high speed road courses and I can tell you the last thing you ever want to do is lock up a tire.

The best thing you can do is let the vehicle regain a neutral balance then apply braking without loosing the ability to steer. I would much rather steer out of a problem than to skid and hope I will survive!

Gary

PineRidge · Feb 10, 2005

We have a pond on our property and last winter I descended the backside of the dam on the TC-40D. It was rather a wild ride from the top to the bottom, kind of a long controlled skid just like the backside of my pants looked after I jumped off the rig at the bottom. /forums/images/graemlins/blush.gif

The dam is now off limits once the snow falls until after early spring. Skids like that are no fun at all.

rbarker · Feb 12, 2005

( I suspect that the engine braking was a big part of the problem. Once traction is broken, there is no way to reduce the engine's braking effect without disengaging the clutch or increasing the engine speed to match the tractor speed.)

Yes, I can see your point. I was thinking the whole "rolling tire vs. locked wheel" issue in which the rolling tire is a better scenario. In this case you could be right, it might not have made any difference. Others seem to agree with you on that as well! /forums/images/graemlins/blush.gif

( Pumping the brakes has been the accepted practice for slowing a vehicle on a slippery surface for many years. It actually reduces the likelyhood of wheel lock. The advent of anti-lock brakes has made the practice obsolete in those vehicles so equipped. )

Of course you are right! I've done it many times prior to having antilock brakes. I guess I was thinking that in this case while traveling down a slippery slope at acccelerating speed it would be pretty easy to lock up a wheel or two with a pump on the brakes. If done carefully it could certainly help.

( The driver of the truck behind me later told me that he could see my rig start to bend in the middle and then straighten out. Definitely a high pucker factor incident. /forums/images/graemlins/grin.gif )

Oh yeah! That'll keep you regular for the day! /forums/images/graemlins/wink.gif

Catch95 · Feb 22, 2005

Thnaks for all the posts on this.

I had to go up and down the same hill the other day and approached the hill with some caution. I had the same implement on the 3PL but not with the PTO engaged - I'm sure it was engaged when I had the problem. I went down the hill even after some rain with no difficulty at all.

So I am fairly sure the problem I had the other week was caused by action of the implement driving me down the hill - as was suggested in a post.

Thanks again for all the advice.

Mark