GUIDELINES FOR SNOWMOBILE TRAIL
           GROOMER OPERATOR TRAINING


A Resource Guide for Trail Grooming Managers and Equipment Operators:


Chapter 2 - Grooming Equipment
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Typical Features of A Multi-Blade Drag:

The following are brief descriptions of the typical features of a multi-blade drag:

Frame:
The frame is typically fabricated from welded steel tubing and painted to inhibit rusting. The frame supplies a rigid foundation onto which the various components are attached and should not bend or twist significantly when stressed by the drag working. If the frame becomes bent or twisted, it can result in the drag cutting or compacting unevenly. Therefore, it is important that the drag’s frame be regularly checked and maintained.

The frame is the major contributor to the weight of the overall unit which is an important design criterion. See examples of typical multi-blade drag frames in Photo 2.1.

            
Photo 2.1 Typical multi-blade frames and blade configurations

Side Rails:
The outside edges of the frame form the skid surfaces upon which the drag slides and are referred to as the side rails. Side rails are important in that they keep the snow that is being processed contained within the inside of the drag frame.

A major difference between multi and single blade drags is that single blade drags do not have side rails.

          
Photo 2.2 Side rail on a multi-blade drag helps keep snow contained within the drag.

Spring Tripping Blades:
As the blades cut off moguls, they can often hit rocks, stumps, or other fixed objects buried in the snow. While not all drags have spring tripping blades (rather they are mounted solid so they do not “trip” when hitting a buried solid object), it is highly desirable that each of the individual cutting blades is spring loaded (see Photo 2.5), so they can trip out of the way if they hit a buried object.

This can help prevent damage to the drag, tractor, and the operator.

                                
Photo 2.3 Spring tripping blades

The cutting blades in some drags are mounted on spring shanks, similar to what are used on agricultural field cultivators and diggers (see Photo 2.6).

                        
Photo 2.4 Spring shank blades

Cutting Blades:
It is desirable for the cutting blades to be slightly beveled so they cut into the mogul versus being mounted straight up and down where the blade would simply skim over the top of moguls (see Photo 2.5).

                        
Photo 2.5 Beveled cutting blades

They are typically mounted in a “stepped” manner where the front row is 5/8” (1.6 cm) below the side rail and the rear row is up to ¾” (1.9 cm) below the side rail.

This provides more cutting depth as the frame is lowered. Also note that blades are typically mounted in an angled manner so they transfer snow from the outside of the trail to the center of the trail where wear is usually the greatest from snowmobile traffic.

                        
Photo 2.6 Serrated cutting blades

Some drags also use serrated blades (see Photo 2.6) in the front row(s) which assist in cutting hard or icy trails.

Tongue:
The tongue on many drags is hinged so it can move up and down at the drag frame, but not from side to side (see Photo 2.7).

                        
Photo 2.7 Pivoting tongue

The up and down movement is controlled by a hydraulic cylinder operated from the tractor’s cab allowing for simultaneous, continuous control of blade cutting depth on multi-blade drags. The tongue may attach to the tractor with either a pintle hitch or a 5th wheel type of hitch. Other drags, particularly those used behind farm tractors, are steered hydraulically by means of a rigid hitch (see Photo 2.8).

                        
Photo 2.8 Rigid steer hitch

Compactor Pan:
The compactor pan should provide for full width smoothing that leaves an evenly finished trail surface free of holes or divots. The front of the pan is angled forward to catch and spread the processed snow evenly across and under the pan (see Photo 2.9).

The rear of the pan has a high radiused lip that aids in “ramping” the drag up onto the snow when backing up in soft snow without the aid of the wheels (see Photo 2.10).

                        
Photo 2.9 Angled front of pan

The bottom of the compactor pan on a multi-blade drag is typically flat steel with wear bars or runners positioned at the two outside edges. Two to three additional replaceable wear bars are often evenly spaced across the center of the underside to help protect the pan surface.

                       
Photo 2.10 Radius lip on rear of pan

Some pans may also be surfaced with either a plastic comb material or sheets of corrugated steel. However, flat steel or corrugated steel is better than plastic for a pan’s bottom since they produce friction which is so important to the trail’s set up.

Skegs
Replaceable hardened steel skegs (runners) are normally mounted on the bottom of the compactor pan. These skegs reduce side hill slippage of the drag and also help prevent premature wear of the compactor pan. They are especially important to “drag steer” groomer configurations whereby the drag acts as the steering rudder for the entire grooming unit. Photo 2.11 shows the telltale marks from packer pan skegs.

                 
Photo 2.11 Skeg marks on a freshly groomed trail

Vibrating Pans:
Vibrating pans are a relatively new feature on multi-blade drags. They utilize a flow control valve and return system to hydraulically “vibrate” the rear pan in an effort to increase compression and aid trail set up.

The hydraulic vibrator is mounted so as to isolate the vibration downward into the trail surface and away from the drag itself. They are most commonly used with agricultural tractors since their hydraulic systems more readily accommodate the operational needs of vibrating pans (see Photo 2.12).

              
Photo 2.12 Typical vibrating rear pans

Wheel Assembly:
The wheel assembly is a set of wheels, mounted either at the rear of the drag or within the frame assembly (see Photo 2.13), that can be raised and lowered by hydraulic controls from the tractor’s cab. During normal grooming operations, the wheels are raised so they are out of the way. When crossing roads or railroad tracks, the wheels are lowered so the drag is picked up off the ground. The wheels are also helpful when backing up the drag.

                     
Photo 2.13 Typical wheel assemblies

Some drags use a rear drum roller rather than wheels. The drum is typically operated like wheels in that it can be hydraulically raised and lowered (see Photo 2.14). It also can be used to aid trail compression and compaction.

                        
Photo 2.14 Typical rear drum roller assembly

Quick Release Features:
The drag may encounter immovable objects such as stumps or rocks that could damage it, the tractor, or the operator. Consequently, a shear bolt is generally used in the hitch that will break away before major damage occurs (see Photo 2.15 – to the right of the pintle).

Quick-release couplings in the hydraulic hoses can also help ensure that the hydraulic system is not torn out in the event the shear pin releases the drag from the tractor.

                     
Photo 2.15 Quick-release couplings and shear pin in tongue of pintle hitch

Single Blade Drags:

Many earlier drag designs, which are still used in some areas, incorporated a single, full-width cutting blade with the idea that it would carry snow and allow it to drop into depressions.

                    
Photo 2.16 Typical single blade drag

Some designs also incorporated a rolling drum in front of the rear compaction pan. This type of drag can work well in areas with frequent, deep snowfall where grooming requires more continuous work to build new base because of frequent snowfall. However, in areas with heavy moguls, the single blade drag can be less effective due to its limitations for fully cutting and processing moguls.

It is important that the tractor be equipped with a front blade to help process moguls in this situation.
Other than number and configuration of blades, the components of a single blade drag are very similar to that of a multi-blade drag.

The operation is different than a multi-blade in that the height of the cutting blade is regulated by a hydraulic cylinder versus by the hitch. Additionally, since this type of drag does not have side rails to keep snow contained within the drag, snow can be easily wasted out the sides if the operator attempts to cut and carry too much snow with the single cutting blade.

                      
Photo 2.17 Typical single cutting blade

Tillers:
A tiller is mounted on the rear of a grooming tractor and is driven hydrostatically (see Photo 2.18). A tiller typically requires deep snow conditions and is used to break up compacted snow surface, to reduce snow and ice chunks, and to mix old and new snow.

                      
Photo 2.18 Typical rear-mounted tiller

The tiller itself is similar to a garden roto-tiller and consists of a rotating shaft (cutter bar), which has multiple tines that are typically three to five inches (7.6 to 12.7 cm) in length that condition the snow when operated at a high RPM, and a plastic comb or “snow finisher”. The tractor’s horsepower must be sufficiently large to operate the tiller.

Benefits of a tractor equipped with a tiller include the extreme portability, ease of backing, ease of turning around, and ease of plowing drifts. Additionally, the unit can be easily stored and easily hauled on a truck or trailer.

A tiller can work well in moist snow, but if there is dry powder snow, it can sometimes be hard to get a good trail since the snow/trail doesn’t stay together.

Therefore, it can be important for there to be good moisture in the snow to get good results and “snow pavement” that lasts.

If the trail is heavily moguled, multiple passes may be required since a tiller can only processes to a maximum depth that is equal to the length of its tines (if it has 3 inch {7.6 cm} tines, then that is the maximum processing depth; if it has 5 inch {12.7 cm} tines, it can process to a maximum depth of 5 inches {12.7 cm}, etc.).

In such cases, a good front blade on the tractor, and an operator who can cut moguls with the front blade, is required to feed enough snow to the tiller for processing and ultimately creating a smooth trail.

It is easy to build a smooth trail with a tiller, but not necessarily a level trail since the unit will bob up and down mirroring what the tracks of the tractor do. It can sometimes also weave side to side. For this reason, they produce better results on an undulating trail with frequent turns and ups and downs versus on a trail with long straightaway sections.

It is recommended that areas also have a drag to supplement trail grooming with a tiller, since it is rare that season-long grooming conditions (weather, snowfall, moisture, and traffic) are consistently favorable for grooming solely with a tiller.

Flex tillers pivot (or flex) in the center and are typically used on downhill ski hills to create terrain features. Some manufacturers provide a lockout device whereby a flex tiller can be locked in a rigid/straight position which is required to groom a flat snowmobile trail surface.

Compactor Bars:

                   
Photo 2.19 Typical compactor bars
A compactor bar, also commonly referred to as a “packer bar,” is a very simple, lightweight implement, short in length and attached to the rear of a tractor, which can be hydraulically lifted completely off the snow to allow the tracked vehicle to easily back up and/or turn quickly in tight spaces.

Some models also have hydraulic down-pressure to help increase compaction. It can be used to significantly reduce the time, effort, and cost of opening a snowmobile trail at the beginning of a grooming season by compacting snow on the trail to set up a firm base for future grooming with a drag.

In swampy areas, it can facilitate compaction that helps drive the frost into the ground and helps freeze the swampy ground faster. The use of a packer bar generally saves wear and tear on a drag during early season trail set up and also provides for increased tractor maneuverability.

A compactor bar can also be used after exceptionally heavy snowfalls during the season or in areas of extreme drifting when a drag can be too much for the tractor to handle effectively. Some packer bars are designed so they can be mounted on the tractor while a drag is simultaneously hooked to the tractor’s pintle hook.

With such a configuration, operators can groom with the drag up to a point on the trail where heavy drifting has occurred, unhook the drag, and continue through the area using just the vehicle’s front blade and the packer bar to establish an initial trail base.

They can then return to the drag, reconnect it to the tractor, and proceed onward while “finishing” the trail with the drag. Some areas “track pack” a trail route, with just the tractor and no drag, after a heavy snowfall or at the beginning of the season when there is deep snow and no established trail route.

It can also be beneficial to track pack early in the season when there is low snowfall since the “crimping” effect of the tracks can help stabilize the snowpack. The use of a compactor bar, particularly when there is deep snow, can greatly increase the effectiveness and efficiency of grooming efforts when there is a need to track pack.




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