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Heavy, wet snow and a brake steer snowcat

caldonia

Member
Jackson Hole is experiencing the biggest snow year I can remember in my 40 + years living here. My 1971 FlexTrac Nodwell is working hard to keep my Sleigh trail groomed. It has been running well all winter in cold soft snow. I can "carve" a smooth turn in this type of snow even while pulling a loaded drag.
Now the snow has gone wet and heavy. Turning is now is a challenge. Lots of sprocket jumping. Is this just a result of difficult conditions or could there be another problem. Can you make a smooth turn in this heavy snow with a brake stear cat? Any one have some experience in these conditions? My grousers are 1" squarestock with 2" angled extensions.
 

redsqwrl

Bronze Member
GOLD Site Supporter
I can't speak directly for your machine, I will however share my concerns of my Spryte.

I have a full cab spryte and the snow here in the upper midwest is extremely heavy and high moisture. the spryte has so much grip that smooth gentle arching turns are out for the season. steering is taking a lot of input and sprockets are skipping just a bit more than normal.
I am placing my turns a bit more carefully and giving sharp input while applying throttle. I am not an expert by any stretch but snow conditions do directly impact my cats steerability.
 

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caldonia

Member
Thanks for the quick reply. Your spryte is just like my Nodwell. Same dimensions and drives the same. I drove a spryte prior to acquiring this Nodwell snow pacer. I guess sproket skips are the norm in these conditions. Just curious as to how to deal with it. Can track adjustment help or is this just something that brake stear cats do?
 

PJL

Well-known member
I noticed the same thing today and yesterday in the LMC1200. Heavy wet snow, temps in the upper 30's. Lots of popping and creaking on downhill right turns. But not uphill when under more power. I had to run one steep spot with a tight corner 4 times today and it seemed to be better if I applied power as I turned. Which seems counterproductive when going down a steep hill. Maybe that's the trick??
 

Snowgeorge

New member
I've got a thiokol imp in Idaho and it rained on about 4 feet of snow this weekend. I have the same issues. I think the sharp inputs and turning vs throttle inputs r key. Also keeping the front end up, like the tip of a ski in powder and Center of Gravity like ind small planes makes a difference.
 

Cletis

New member
Caldonia, I believe some of the groomers back east use a ram steer set up to help turn. We're having a fairly decent, (not epic), snow yr in the Bighorn mountains also. Just powder, not the wet stuff.
 

caldonia

Member
Why didn't I think of that. Put ait ski up front and I'm back to carving turns.

Thanks for all the replys. Heavy, wet snow just sucks!
 

Snowcat Pat

Active member
PJL and Redsqwrl, described the method.

When its bad like that its worse with a heavy load and downhill. Downhill is the time I get the most problem with jumps. The outside track seems to be dragging the inside track right over its sprocket.

What I do to minimize the jumping (and worrying the passengers) is to slow way down before the turn, apply the brake and accelerate simultaneously through the entire turn (that's why slow way down first ) then let go the stick before letting off the throttle. I also put the outside track in the soft snow to give someplace for power to go so I'm not going too fast at the end of the turn.

Its the same with every two track I've driven. Sprocket jumping is not good for the diff.

If I were towing a drag I would outfit the machine with ram steer. Towing something makes the machine want to go only in a straight line.

-Pat
 
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JimVT

Bronze Member
GOLD Site Supporter
Jackson Hole is experiencing the biggest snow year I can remember in my 40 + years living here. My 1971 FlexTrac Nodwell is working hard to keep my Sleigh trail groomed. It has been running well all winter in cold soft snow. I can "carve" a smooth turn in this type of snow even while pulling a loaded drag.
Now the snow has gone wet and heavy. Turning is now is a challenge. Lots of sprocket jumping. Is this just a result of difficult conditions or could there be another problem. Can you make a smooth turn in this heavy snow with a brake stear cat? Any one have some experience in these conditions? My grousers are 1" squarestock with 2" angled extensions.
wet snow doesn't flow out of the tracks like dry. could it be building up or packing into ice?
I had to build ice scrapers for my snow trac because of the wet snow sticking to my drive sprockets.
jim
 

PJL

Well-known member
Snowcat Pat, thanks for confirming my observations. I'm still learning the quirks of this machine. Supposed to go out tomorrow for a big training event so I will get more time in the wet snow. Since it's raining now it's gonna be like driving in wet concrete.
 

tatman

Member
SUPER Site Supporter
Its hard to believe that you guys are getting so much snow over there. This is the least amount of snow we have had on our mountains since I started snowmobiling 27 years ago. Fences that are normally buried you can see the bottom rails. Were only 120 miles away as the crow flies. Send some over the hill.
 

caldonia

Member
Thank you all for your replys and suggestions. I have had this difficult steering issue before and believed it was simply snow conditions but wanted make sure.
It's raining now and heavy and moist has turned to slush. The steering is fine. Go figure. We are getting rain on an unusually big snowpack the Jackson Hole is closed. No way in or out due to avalanches closing all routes in and out of the valley. Power to the Mountain Resort is out due to power line failure. Glad I have a snow cat in my quiver of vehicles.

Though my question was answered it brings up another. What is "ram steer" and how does it enhance a brake steer cat?

I'll post this as a new thread.
 

PJL

Well-known member
This was a very informative thread. Our training today was cancelled to due to horrible weather and the very real risk of avalanches along our route. It's 50 now and raining hard. I stayed inside and worked on a Huey instead.

Tatman you can have it. Act fast, it's rapidly turning into liquid and draining into Puget Sound.
 
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turbinator62

Active member
Site Supporter
SUPER Site Supporter
I have the same problem with my Imp when going downhill, especially when turning. No problem going uphill.

Here's my theory: On a rear sprocket machine when going uphill, the bottom of the track is tight (top is slack) and stays at its correct pitch for the sprocket, so it rides correctly in the sprocket teeth. (Unless it is really loose) When going downhill, the bottom of the track is slack, (top is tight) and tends to bunch up which shortens the track pitch slightly, causing it to ride up on the sprocket until it is tight and then jumps into the bottom of the tooth. (Like a bicycle with a worn chain) This more pronounced on the side with brake applied.

I keep my track fairly snug but it still does it. The 1402 uses a 3 position adjustable front idler which is then inflated to 65-70 psi to maintain track tension. When going downhill there is more visible "squish" of the tire than when going uphill.

The imp manual says that tooth jumping is normal and not a problem, and in fact cautions against running it too tight.

My imp has the 12 tooth wheel sprocket which doesn't have very deep teeth, so I thought that was the part of the problem, but apparently I am not alone.
 

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sno-drifter

Bronze Member
GOLD Site Supporter
Easy turn up hill and hard down hill has to do with gravity. Often when operating a Caterpillar tractor on down hill stretches, the outside track can be disengaged and that side will speed up making the turn. To help the turn, reduce the engine speed and this slows the inside track and lets the outside track go faster and makes the turn. Down hill turns require the brake to overcome gravity and then do the friction for the turn.This applies to older Cats like 2-U, 18-A, 7-U, etc. Don't know about the new stuff. And don't know about two track snow machines, might work if the machine has right and left clutches.
 

loggah

Active member
SUPER Site Supporter
I know wet snow lubricates the sprockets more and that allows them to jump while trying to turn going downhill. The reps from bombardier used to say it was nothing to worry about. They recomended turning a bit,let off go a bit further and turn again, basically pumping the steering lever a bit.
 
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