Wheels and Axles

Gears, Sprockets, Axles, and Axle Hardware

Axle

Axles provided by the Tetrix build system are D-shaft axles of various lengths and diameter. A D-shaft axle had a grinded flat edge on one side of the full length of the piece. This flat edge allows for additional elements to be mounted to it using set pins. A properly tightened set pin lined up with the flat edge of a D-shaft axle will create a very strong assembly. The tetrix axles come in two diameters, a 4.7mm and a 6mm. The 6mm matches the diameter of the motor shafts on the tetrix provided motors. The 4.7 mm axle comes in 100mm (3.94 inches) and 250mm (9.8 inches.) The 6mm motor shaft axle comes in one size of 100mm.

Bushing

Bushings, (sometimes called plain bearings, plain bushings, or sleeve bearings) reduce friction between two surfaces sliding against each other. Bushings work because of a principle that when two dissimilar metals are rubbing on each other, they have a lower coefficient of friction than like metals- this principle is bolstered when one of the metals is bronze. The Tetrix Bushing is bronze with an inside diameter of 4.75mm and an outside diameter of 8mm. This allows for the 4.7mm axle to fit snug and glide on the inside and have a good fit in the center 8mm hole of a structural tetrix element. The bushings come in two sizes, 11mm and 4mm, and also have a variant that fits motor shafts where the inside diameter is 6mm.

Axle Set Collar

An Axle set collar is designed to lock a rotating axle and secure the horizontal alignment. When the set screw is tightened over the flat edge of a D-shaft axle the set collar will secure the side of the axle from moving past a structural element face. The tetrix set collars have an inside diameter of 4.75 mm which allows for a 4.7mm axle to fit perfectly with an outside diameter of 10.7 mm which is wider than the bushing face or 8mm hole on a structural element face.

Axle Hub and Motor Hub

The Axle and Motor Hubs are used to attach gears, wheels, and structural elements to axles and motor shafts. They do this by mounting on the D-shaft axle and tightening their set pin on the flat edge just like the Axel Set Collar. Each hub has a protrusion that is 8mm in diameter that lines itself up concentric with a wheel, gear, sprocket, or center of a structural element. This is important to make sure any rotating elements are centered on the axle. The inside diameter matches to fit on a 4.7 mm axle or a 6mm motor shaft. The four holes on the face of the hub are tapped with a 6-32 screw thread that allows you to secure whatever you are mounting to the hub using a 6-32 Socket Head bolt without the need of an additional nut.

All Terrain Tire Mount

The All Terrain Tire Mount is used to attach All Terrain Tires to axles and motor shafts. They do this by mounting on the D-shaft axle and tightening their set pin on the flat edge just like the Axel Set Collar. The inside diameter matches to fit on a 4.7 mm axle or a 6mm motor shaft. The hole on the top face of the mount is tapped with a 6-32 screw thread that allows you to secure whatever you are mounting to the hub using a 6-32 Socket Head bolt without the need of an additional nut.

Wheels and Tires

Tetrix MAX Wheel

The Tetrix MAX Wheel is comprised of a nylon wheel with neoprene rubber tire. The rubber tire provides ample traction on the floor especially when competing on the foam tile field of First Tech Challenge. The wheel has a center 8mm hole surround by four 9/64 holes that allows for mounting to a Axle or Motor Hub. The tire width is 25.4mm (1 inch) and comes in two sizes, 3" or 4".

Omni Wheel

The Tetrix Omni Wheel is comprised of a nylon wheel with 10 neoprene rollers that can freely and independently spin. These wheels have the ability to drive forward and laterally. The wheel has a center 8mm hole surround by four 9/64 holes that allows for mounting to a Axle or Motor Hub. The Omni wheel comes in two sizes, 3" or 4".

Mecanum Wheel

These wheels are designed to use four motors each controlling one wheel, so now your robot can move at any angle without turning and with smoother motion using holonomic behavior. Aligning with the Tetrix hole pattern, the wheels come fully assembled, including the hub, and are a breeze to attach to your Tetrix robot. This wheel is made of a durable Delrin plastic inner core, high-strength blue anodized aluminum roller plates, a Delrin plastic inner roller core, and molded-on rubber outer roller, all built on steel roller pins, these Mecanum wheels are made for intense competition. You can confidently support a 65-pound robot when four of the TETRIX Mecanum Wheels are used as drive wheels. The hubs feature a 6 mm D-shaft compatible with the TETRIX MAX TorqueNADO® Motor and TETRIX 6 mm Axles. Primarily used as drive wheels, the full set consists of two A wheels and two B wheels and should be configured in an X pattern (A on front left and rear right and B on front right and rear left) when your robot is viewed from above.

All Terrain Tire

These All Terrain Tires have a better grip for climbing or taking on uneven or rough surfaces – and get a monster-truck look at the same time! This tire can also act as a compliant wheel where the tire tread has a little squish factor to help it grab surfaces. The tire consists of a nylon rim and neoprene rubber tire. You can also choose to put foam inserts inside the hollow tired to increase the firmness of the wheel. This tire requires the All Terrain Tire Mount to mount it to an axle or motor shaft.

Spacing Hardware

Round Spacer

The Round Spacer is a lightweight aluminum spacer that is exactly half the width of Tetrix Channels and feature four tapped holes to provide secure 16 mm spacing between Tetrix structural elements. They can also come where the four holes are untapped through holes allowing a bolt to pass through. These handy spacers are useful for obtaining proper gear mesh spacing when building geared servo mechanisms and for a variety of other adjustments and attachment needs.

Round Spacer

The Round Spacer is ideal for maintaining proper distance between two Tetrix elements attached on either side of a structural part. The flat round spacer is 2 mm thick – the same wall thickness as Textrix structural elements- this makes it perfect to act as a washer to add space where needed to line up to other tetrix parts. The inside diameter is 8mm (.31 inches) and the outside diameter is 27mm (1.06 inches) The patterns of the holes are identical to the other hole patterns on Tetrix's structural elements.

Simple Assemblies

Spinning Axle, Hub, and Collar

The Assembly to the right demonstrates the proper way to create a free spinning axle. The axle is inserted through two bushings on either side of a channel- when making a spinning axle, the axle must be supported by at least two points making a channel ideal for the application. The bushings allow the axle to be concentric to the channel and lower friction while spinning. On one end of the axle, secure a axle hub to the axle- this will allow you to mount a wheel, gear, sprocket, or other tetrix element. To secure the axle from falling out, a collar must be placed one the axle flush to bushing face. Note how both set pins are aligned with the flat edge of the D-shaft axle. Tighten your set pins on this flat edge to secure the axle and prevent slipping.

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