Snowblower Term Glossary
The Gilson Snowblower Shop

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This is an explanation of terms you will find on this site. I have tried to include terms that are of general use as well as those specialized to the Gilson line. I'll try to stay with the definition here, applications of most terms can be found elsewhere on this site.

2 stage: See dual stage

2 stroke (2 cycle): An engine design that delivers power on every down stroke. Engines are capable of high RPM operation. 2 stroke engines use gasoline to which lubricating oil has been added at a prescribed ratio. These engines have high power to weight ration and are often found in compact snowblowers. Also common in chainsaws and leaf blowers.

3 (triple) stage snowblower: Essentially a 2 stage snowblower with a second overhead auger designed to pull drifts and banks down to the primary auger. Most common on machines from the 1970s

4 stroke (4 cycle): An engine that delivers power on every other down stroke as in a common automobile engine. Engines are lubricated from a sump of crankcase oil with either a splashing mechanism or an oil pump. Higher HP engines are built in this configuration.

Auger (2 (or dual) stage: On 2 stage machines it refers to the relatively slower moving helical parts that collect the snow, move it to the center and feed it back to the impeller.

Auger (single stage) On single stage machines it refers to the spinning member that collects and throws the snow. On single stage machines the terms is used interchangeably with impeller and rotor.

Bell crank: A linkage plate that connects two control rods and pivots on a third point. Used to change directions in a control linkage.The proprtions of the arms can also increase or decrease the amount of movement at the endpoint.

Bucket: Refers to the front half of a snowblower that typically includes the auger, impeller skids, scraper bar and chute.

Chute: The components that snow is discharged through. Normally rotates slightly more that turn and has a top half that can be pivoted to change the distance snow is thrown.

Clevis pin: A pin used to link a wheel to an axle in this application. The pin is retained with either a cotter pin or hair pin cotter AKA hitch pin clip.

Click Pin: A pin used to link a wheel to an axle. The pin has a spring loaded hoop that when sprung in captures the pin on the shaft. When opened it becomes a handle for pin removal.

Compact Snowblower: (The term as I use it) The class of push style snowblowers ranging up to 7 HP. The auger drum has rubber flights that move the snow and pull the machine forward as they scrub snow from the ground. Generally powered by 2 stroke engines however some larger units use 4 stroke engines. The Gilson entry in this market was called the Snow Cannon.

Deflector: The top section of the discharge chute. It can usually be pivoted to control how far the snow is thrown.

Drift Breaker: Steel bar projecting up and forward from the bucket. It can be used to twitch drifted or banked snow down for the snowblower to collect it. Also it often serves as a service stand letting the machine stand on its nose to allow servicing of underside components.

Dual Stage: A snow blower with a low speed auger that loosens and collects the snow and a higher speed impeller that hurls it up the discharge chute.

EOD: A newsgroup expression for the snow bank at the End OF Driveway.

Friction Wheel: A steel wheel with a bonded rubber surface. When driven against a driven platter at specific radii it forms the basis of a simple transmission used to drive the wheels.

Flights: The rubber/composite surfaces used to move snow in compact snowblowers. They are attached to the auger drum

Gear Drive: Refers to a family of Gilson snowblowers. Power is transmitted from the engine by belt but all speed selections and final drive transmission is done with sealed transmission, cogs, sprockets and chains.

Governor: A mechanism used on small engines to regulate engine speed. The throttle control can be set to any speed including full and the engine will run at that speed. If the engine slows down due to an increased load the governor will try to compensate by increasing the air / fuel flow.

Hair Pin Cotter: A substitute for a cotter pin that can be easily removed and reinstalled, see picture.

Hard Rubber (tires): Tires that are either cast on the rim or the rim is built around the tire. They are very difficult to replace and wear poorly. Replacements are rarely available.

Hitch Pin Clip: see Hair Pin Cotter

Hypro Key: An obscure form of shaft coupling key used by Gilson. It is essentially a woodruff key with an extended projection above the shaft surface. They may also be found as hi-pro keys and under other spelling varriations.

Idler (Idler Roller): A freewheeling roller with some sort of internal bearing that presses against a drive belt to apply tension. Often connected to a linkage that allows control of the tension to form a clutch.

Impeller (2 (or dual) stage): On 2 stage machines it is the fan like part that spins at a high speeds and propels the snow up out of the machine. Common variations have 4 to 6 blades. On a few vintage models from companies such as Simplicity and Bobcat they are of a paddle wheel design.

Impeller (single stage) On single stage machines it refers to the spinning member that collects and throws the snow. On single stage machines the terms is used interchangeably with auger and rotor.

Interlock: In this context a system of electrical switches that insure the operator is in the safe position whenever the machine moves or the blower system is operating.

Lead: (lēd) The helical band of an auger that moves the snow.

L-Head: Traditional small engine design that has the valves positioned to the side of the combustion chamber. Manufacturers are phasing this design out.

Master Link: On roller chain it is a link that has a clip allowing installation and removal without special tools. Typically only one is used per length of chain.

Mitt Guard: A guard found on the discharge chute designed to let the snow exit but to prevent the operator from sticking a hand into the chute.

OHV :(Over Head Valve) Newer cleaner and more efficient engine design that has the valves positioned over the combustion chamber.

OPE: Outdoor Power Equipment. Refers to the entire realm of yard and garden implements with engines.

Pneumatic (tires) Tires with or without tubes that are filled with compressed air usually on the order of 10 PSI. Generic replacements are readily available.

Roller Chain: Power transmission chain as used on a bicycle. Usually specified as an ANSI size and link count. A generic item.

Rotor On single stage machines it refers to the spinning member that collects and throws the snow. On single stage machines the terms is used interchangeably with impeller and auger.

Scraper bar: A heavy steel bar with a sharp edge mounted to the bottom of the bucket. It's primary function is to provide an edge that will allow the machine to cut through the snow. It also stiffens the bottom of the bucket in most cases.

Semi Pneumatic (tires): Tires that approximate the look and feel of pneumatic tires. The walls are generally thicker to provide the needed support. Replacements are rarely available.

Shear Pins (Shear Bolts): Sacrificial pins or bolts used to connect a portion of the power train, usually the augers to their supporting shaft. They are sized and made of material that will shear before damage occurs to the machine. Analogous to an electrical fuse.

Single Stage: A snowblower that accomplishes all snow handling with one high speed auger, impeller, or rotor as the manufacturer choses to call it. There are two distinct classes of these machine.

  • One version has an engine ranging from 2 to 7 HP that drives a rubber/composite auger that blows the snow and makes enough ground contact to pull the machine forward into the show. These machines are pulled back by the operator. Except for the largest they generally have 2 stroke engines

  • The second version is found in some tractor attachments and some (vintage) walk behind machines. These have an all steel auger that does all of the snow handling and the machine is self propelled just like a full size 2 stage machine. These machines will have 4 stroke engines.

Skids: Steel plates mounted to the sides of the front bucket. Their purpose is to support the machine at a preset distance above the ground. They are adjusted by the user according to the surface the machine is being used on.

Snow Engine: Sold with trade names such as SnowGard, SnoKing etc. Generally a standard engine with modifications such as: no air filter, a heater box that uses muffler heat to preheat intake air, shrouding to keep snow out of the recoil, a mitten friendly rope handle, a gas cap with a shrouded vent to prevent water entry, a rubber boot on the spark plug to prevent ignition interuption.

Tire Chain: A web of link chain that encircles the tire to enhance traction. Modern tires have made this accessory nearly obsolete except in severe conditions or with worn tires.

UniTrol: A Gilson friction driven machine. Gilson patented the linkage that raised the wheel above the platter and positioned it for the desired speed with a single lever. Gilson expanded the concept to a tractor and roto-tiller in latter years.

Worm drive: A pair of gears designed to transmit power at right angles. Usually found at the center of the auger assembly. The gears provide a speed reduction between the impeller and the auger. The drive case may be filled with an oil lubricant or packed with grease depending on the design. The worm looks like a screw and is usually made of steel. The worm wheel looks like a common gear cut to mesh with the worm, it is often made of a bronze alloy. The combination of metals makes for a cooler running gear set and the bronze worm wheel becomes a sacrificial component.

Zerk: A common style of grease fitting for use with a high-pressure grease gun.

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Created October 2003