GUIDELINES FOR SNOWMOBILE TRAIL
           GROOMER OPERATOR TRAINING


A Resource Guide for Trail Grooming Managers and Equipment Operators:


Chapter 4 - Operating Grooming Equipment
      .
Grooming Basics

Tips for Grooming With a Tiller:

Preparing Fresh Snow:
Fresh snow initially creates a generous crystalline microstructure that is more or less jagged. Fresh snow should be worked as gently as possible since snow crystals are destroyed if a tiller is used too aggressively, causing snow crystals to no longer bond with one another and to become slush.

Fresh snow/powder snow consists of snow crystals which hang together loosely and thereby enclose a lot of air. When preparing this type of snow, part of the air is driven out and the crystals are pressed closer together, which gives the snow a load bearing coating.

Processing Moguls:
Moguls are sometimes formed as snow crystals melt as a result of water film formation occurring from traffic on trails. This can result in a combination of ice slabs and also 70 softer areas (moguls) as snowmobiles break the top layer of snow. Ideally, old and relatively “fresh” snows (snow crystals) are mixed to produce a durable trail. When temperatures are sufficiently low, the snow freezes into chunks.

The tiller’s teeth smash the chunks of snow into slush, which fills the gaps on the surface of the trail. This processed snow/slush is then shaped by the finisher/comb and bound together by water film formation. As the chunks are smashed, the snow crystals are also destroyed so bonding only takes place to a limited extent.

This is why slush can only be created from ice and never from powder snow. A durable snow surface is only produced as a result of mixing the processed snow with fresh snow and/or by mixing the snow on top of the trail with old snow which is lying at lower levels, beneath the top of the trail surface, and has not yet been used.

Processing Icy Surfaces:
Icy trail surfaces should only be broken open if the snow coating is strong enough or if fresh snow has fallen. Slush created in this way will only bond with fresh snow or water – again forming ice. Ice slabs formed in snow surfaces which are otherwise good can be processed by mixing them with snow crystals lying deeper in the snow. However, the more frequently the snow is turned over and the crystals are destroyed, the less the crystals will bond together.

Processing Wet Snow:
A relatively hard surface may be formed on the snow surface as the result of high humidity which can cause a film of water to develop on the finisher/comb. Sometimes tilt options on tillers can be used to cope with this to help break up this glazing effect.

Processing Extreme Sugar Snow:
When grooming in conditions where there is extreme sugar (very fine, dry) snow, particularly in the spring, it may be desirable to use only a smoothing board. Operating the tiller in these conditions can create “side walls” caused by banks of snow spilling out the sides of the tiller. When sugar snow has fallen, it is difficult to create a durable snow surface. Therefore it is a good idea to leave the snow alone for two or three hours, until the temperature changes, so that crystals can form.

Control the Ground Speed:
The goal of trail grooming is to create a snow surface that is smooth and even. If the tractor is driven too fast, the tracks will throw snow out to the side and also over the top of the tiller onto the snow surface which has already been prepared. Too fast of a speed can also cause the tiller to bounce and sway, resulting in an uneven surface.

Operate Only with Sufficient Snow Cover:
Never operate the tiller until snow cover is deep enough to prevent damage to under-lying turf and to the grooming unit. When possible, create snow reserves in critical areas where snow may melt back and expose bare ground.

Proper Tiller Depth:
Indications that the tiller depth is set correctly include:
• perfectly clean snow surface behind the tiller
• the snow surface retains a firm base
• economical operation of the grooming unit
• favorable loading for the tractor and tiller
   Indications that the tiller depth is set incorrectly  
   include:
• rotary shaft set too high: no output visible behind the
   tiller
• no marking at hard points on snow surface
• rotary shaft set too deep: too little snow through-flow,
   so snow flows out of the side of the tiller and forms a
   side wall
• snow crystal bonding and the base quality
   deteriorate
• large amounts of power required – not economical

Side Walls Being Formed by Tiller:
Side walls being formed to the left and right of the tiller indicate:
• excessive groundspeed
• excessive engine speed
• tiller depth set too deep
• contact pressure position switched “ON” rather than 
   in “Float” position
• cylinder equipment carrier has been adjusted
• rotary shaft is at a standstill
• the lateral finisher/comb must overlap the prepared
   track to ensure that the transition between tracks
   occurs in a clean manner

Don’t Leave Holes or Piles of Snow
Any holes in the trail surface and/or piles of snow created when driving or turning the unit should be flattened out again as quickly as possible.

Trail Surface Does Not Look Good:
When parts of the trail do not look good, like they were not processed and finished okay, it may indicate:
• the tiller is set too high – check shaft depth
   adjustment
• engine speed too slow
• lever not in engaged (float) position
• excessive groundspeed Photo 4.16 Properly finished
   trail
• failure to use front tractor blade to create an even
   surface area on the trail, so the tiller is lying “open”
   on moguls

       

Remove Snow from the Unit:
Regularly remove snow that can build up on the loading/cargo area of the tractor since the increased weight will cause increased levels of fuel consumption, as well as affect the unit’s center of gravity.

Groomer is Almost at a Standstill:
If the vehicle is almost at a standstill, it may indicate:
• tiller is set too deep – check shaft depth adjustment
• excessive engine speed
• cylinder equipment carrier adjusted by mistake
• direction of tiller rotation set to contra-rotation
• rotary shaft at a standstill (jammed, crushed, frozen)

Violent Vibration When Tiller Turned On:
If there are violent vibrations in the vehicle when the tiller is turned “ON,” it may indicate:
• the shaft is unbalanced
• a gear is missing as a result of improper
   maintenance
• snow is frozen on the shaft

Unbalanced means vibration – screws unfasten themselves and bearing can be destroyed. This is unsafe, so ALWAYS rectify imbalance immediately.

Operating on Hills or Steep Slopes:
When driving uphill, always only drive with the amount of power necessary and watch out for track engagement/traction. If excessive power is used, the tracks will spin and/or the entire machine will dig itself in. If the tracks begin to dig themselves in, stop immediately and look for a new route.

When driving downhill, always drive at a moderate speed to ensure the engine does not over-rev, the unit does not drift sideways in an uncontrolled manner, and that it does not pull snow down the slope behind it. Drive with as few steering movements as possible while ensuring that both tracks are turning. Speed must be reduced when driving over hilltops to ensure the machine tilts forward in a controlled manner to ensure the front blade does not “stick in the ground” and the tracks do not slip.

If, when driving downhill, the tractor should start to slip and drift sideways to the left or right (vehicle’s longitudinal axle at right angles to the fall line of the hill), immediately counter-steer up to the point where the tracks contra-rotate (by turning steering wheel to the left or right until it locks) to ensure that the vehicle’s longitudinal axle is again pointing in the direction of the fall line.

Briefly increase speed to do this. When the vehicle is slipping in the fall line, reduce the slipping movement by changing over (reversing) the rotary shaft direction of the tiller and by carefully using the front blade as an anchor point. Continue to do so until the vehicle is stabilized.



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