Track Systems

One of the most common questions about this hobby is: How do you build the tracks?, usually followed quickly by It must be pretty hard. As this article explains, there are quite a few techniques for building effective tank tracks and in the grand scheme of things, it really isn't that hard. All of the track systems described in this article can be built using commonly available materials, with commonly available tools and, best of all, a minimum level of working skills. More importantly, given the range of effective track techniques, you should be able to find at least one that suits your particular set of requirements, be they operational, financial or cosmetic.

For purposes of discussion and comparison, we focus on the following characteristics of each track system:

Construction,

Performance, and

Affordability.

The first R/C tank track was built using two bicycle chains and wooden treads that were connected using aluminum 1/8" pop rivets. Such an approach is easy to build and low-cost. Battlefield experience has shown that they aren't as durable as other track systems shown here, but it was the first track design to roll into battle.

The treads were originally made using 1/8" hobby plywood that was ripped into 3/4" wide strips and then cut to 4" lengths (the scale tread width for the Tiger-1). Similar bicycle chain tracks were built using 1/8" steel plate (with steel rivets) and with 1/4" masonite. At the present time, 1/4" masonite is the preferred tread material, because it is very durable, readily available and provides more grip for the rivets to hold it in place.

A bicycle chain track can be built in a few evenings after the materials are acquired. One night to cut and drill all of the treads (boring job, but few skills required), another night to waterproof all of the treads and one final night to assemble everything.

As shown here, the first bicycle track system was designed to be driven by bicycle sprockets. Each sprocket had every other tooth missing (or removed) and a tread was attached to every other chain link, so that the teeth could engage alternating links. This also required the treads to be 3/4" wide, instead of the full 1" width, so that the tread wouldn't interfere with the sprocket teeth.

Unfortunately, bicycle sprockets and chains are essentially designed to easily derail. Although this is a good thing on a 10 speed bike, it doesn't make for a reliable track system. So, after many attempts to keep everything aligned and "on track", the sprockets were removed and a rubber friction drive wheel was used instead (as shown in the picture above).

The amount of traction provided by a bicycle track is very good, because the rivets used to attach the treads to the chain dig into the ground. This is very beneficial for straight-line movement, but also makes it more difficult to turn the tracks. Accordingly, the drive motors used with bicycle chain tracks need to have lots of power.

Friction drive wheels allow the use of full width (1 inch) treads on the tracks, which helps to reduce the possibility of something getting lodged between the treads. Furthermore, by narrowing the gaps between the treads, it is easier to travel over softer surfaces.

Bicycle chain tracks are very affordable. New bicycle chains cost about $4 for a 5 foot chain and you'll need 3 of them for the average size tank track (approx 6 foot in circumference). Wooden or masonite treads (72 per 6 foot track) can be cut from a 2 sq. ft. panel scraps or remnants from a lumber yard, which are normally very inexpensive or sometimes free. You'll also need 144 pop rivets (heck, splurge and get 150), which costs a couple bucks per box of 100. Finally, you'll need to cut drive and idler wheels out of 3/4" plywood and glue or nail some rubber bungee cords to them. All totaled, you're looking at less than $20 per track if you are reasonably good at scrounging and finding bargains.

Steve Tyng developed the Tyng Track System (TTS) for his T-34 using a surplus treadmill belt, with wooden treads and guide teeth that are attached with glue and brads.

A treadmill track can be built using commonly available wood tools and your favorite wood (or imitation-wood) material. Steve Tyng has provided excellent step-by-step photos and a detailed description of the construction process for his T-34 "Tiger Killer" tank, so we'll only summarize the building process here.

Essentially, if you can use a table saw or band, have some scrap lumber laying around and, most importantly, can scrounge a piece of surplus treadmill belt from your local gym, then you can build a treadmill track. The process is a little more involved then building a bicycle chain track, so plan a few more evenings, but each step is straight-forward. Treads and guide teeth are attached with glue and brad nails (or screws if you prefer) to the treadmill belt.

Like a bicycle chain track, a treadmill track is driven by friction drive wheels, which are usually made from plywood and rubber. This means that the tracks must be properly tensioned and the friction surface must be kept clean. Unlike a bicycle chain track, however, the drive wheel used for a treadmill track must consist of two friction wheels with a gap in between to allow the guide teeth to perform their job properly. Although this reduces the overall friction surface, there is still sufficient surface area to drive the track.

Because of the continuous, flexible belt used, a treadmill track can easily travel over a variety of surfaces. The edges of the tread provide excellent traction, while the belt prevents objects from getting caught between the treads. In initial field trials, the tracks proved to be very good in deep snow, which is a very difficult surface for R/C track systems.

A treadmill track weighs about 3 lbs for a 6 foot long track, depending on the type of tread material used.

If you're good at scrounging, treadmill tracks are very affordable. First and foremost, you'll have to acquire a surplus treadmill belt from a local gym. Since they replace them regularly and probably don't have any use for them, with a little bit of asking, you can probably get one for free. (The average treadmill belt is large enough to make a number of tracks, so you might also be able to snag enough material from someone else who has already scrounged some for themselves.)

Assuming you've scrounged a treadmill belt and if you've got a reasonable supply of scrap wood, wood glue and brads in the workshop, then the total cost could be $0 for a complete set of tracks and drive wheels. Builders without surplus materials in the shop will have to purchase about 4 sq. ft. of wood (or your favorite wood-substitute) and some rubber bungee cords for the friction drive. Even with those expenses, the cost of a treadmill track is probably less than $10 per track.

A true sprocket-drive track system can be built using the heavy-duty cousin of bicycle chain known as roller chain. A specific form of roller chain, called attachment chain or conveyor chain, has built-in flanges that can be used to easily attach treads to form a track. Roller chain tracks were first developed by Mike Blattau and Will Montgomery for the hobby.

Unlike bicycle chain tracks, roller chain tracks use a single chain that goes down the middle of the track. A toothed drive sprocket is used to move the track along, and a toothed idler sprocket is used to keep the track straight. Wooden, masonite or plastic treads are attached to the roller chain attachments using rivets or screws.

Roller chain comes in a variety of sizes and strengths. For light tanks and half-tracks, #40 attachment chain (1/2" long links) can be used to support a 2 to 3 inch wide track. For heavy tanks with wider tracks, #60 attachment chain (3/4" long links) is a better choice, and the best choice is #2060 attachment chain (1.5" long links).

Because of the way that attachment chain is made, full width treads can be used without interfering with the sprocket teeth. This allows the track to more easily roll over soft surfaces (like sand or snow), but also limits the flexibility of the track.

Roller chain has very good lateral strength, especially the #2060 chain, which significantly reduces the possibility of the track being pushed out of alignment. In fact, #2060 chain is virtually impossible to twist or bend in any direction. That makes it more difficult to install, but once it is installed it will roll along with any problems for a long, long time.

Roller chain is used in many industries for a variety of purposes, which helps reduce the acquisition cost, but it can still be pricey when purchased new. Fortunately, surplus supplies exist and Will Montgomery has acquired enough to supply about 30 heavy tanks, at a cost of about $2 per foot, which represents a great savings over retail prices.

Heavy duty drive and idler sprockets can be purchased in a variety of sizes, from a wide variety of places for about $15. Idler sprockets with ball-bearings are more expensive, but roll more easily than idler sprockets that use bushings. Given the relatively low speed of an R/C tank, bushings are probably sufficient for idler sprockets and can help reduce the overall cost.

Much like the other tracks discussed so far, any type of tread material can be used, depending on your preferences and wallet. Therefore the cost of tread material for a roller chain track is the same as a bicycle chain or treadmill track system.

Plastic conveyor chains and belts are used in many industries as a strong, lightweight alternative to roller chain solutions. Joe Sommer has incorporated such technology as a track system in his Hetzer Tank Destroyer (#T010).

One of the big advantages of a plastic conveyor track system is that there is no construction necessary. The necessary belt links and drive sprockets must be purchased together, and once received, you simply make the track the right length and mount it on the vehicle. It certainly doesn't get any easier than that (unless, of course, someone came with the package and installed it for you!!)

On the other hand, unlike the other track systems, there is also no real way to modify the tracks either. The conveyor belts come in certain widths, colors and configurations, none of which are easily altered. If everything works great, then that's not a problem.

The initial field tests of plastic conveyor tracks have shown that it works very well with regard to staying on track. The manufactured links and sprockets work well together, without a sound. The durability of the plastic parts is very good (after all, they are made for industrial applications) and they are virtually impervious to the elements.

One major benefit of plastic conveyor track is that it is strong, but lightweight. A typical 6 foot long section of track only weighs about 1.5 lbs, which is the lightest weight of all tracks described in this article.

Plastic conveyor track is strong, lightweight and easy to install, but those advantages come at a relatively high cost. The plastic conveyor links run about $7 per foot, with the drive and idler sprockets costing about $36, for a total cost of approximately $78 per track. That's the highest cost of any track described in this article. So, as in many real-world situations, you get way you pay for: fast and light costs money. (Those who want to spend the money will think it's a great investment, those who don't will find lots of reasons not to go that way.)

See Plastic Track Notes for additional details concerning the plastic track system discussed in this section, including where they can be purchased and the part numbers for various components.

See Track Pad Molding for step-by-step instructions for molding rubber cleats onto each link for added traction in rough terrain and quiet running on flat surfaces.

Molding mass produced parts is one of the primary modeling techniques and Garnet Galenzoski has applied that technique in the development of a molded track for his Leopard Tank (#T011).

For those who have molded parts before, the process is straight-forward, but time-consuming, especially when making hundreds of parts. The construction time, however, is balanced by the fact that hundreds of parts can be made that are essentially identical, with as little or as much detail as desired.

Garnet provides a collection of photos on his T011 web page that shows the various plugs, molds and finished parts that went into his track. Once put together and finished properly, the track will look very close to the original and will probably perform in a similar fashion.

At this time, no field test information is available for molded tracks, but in theory they should behave in a manner similar to any solid track system on both hard and soft surfaces. The molded track should have the advantage of flexibility, which should work well with any suspension system that may be used.

Perhaps the biggest drawback of a molded track system is its reliability. With literally hundreds of separate parts and connectors, there is probably an increased chance for breakage of some sort. Moreover, just like their full-size cousins, if the weakest link fails, the entire track will become in-operational. This is not a concern for the other linked track systems because they rely on industrially manufactured chains which are far stronger than necessary for an R/C vehicle. (The treadmill track system is better still in this regard, because it doesn't have any links at all, weak or otherwise.)

However, without actual field data at this time, it is impossible to determine if such molded links will be durable enough or not. We'll just have to wait and see.

At this time, there is no solid data on the cost of a molded track. Molding resins and materials come in a wide array of strengths and costs. In general, the cost of making a molded version of something is usually higher than a custom made one-shot version of the same thing. However, once the molds exist and the process is understood, it is generally less costly to produce a batch of parts for subsequent copies.

Chrys Kanellopoulos developed a track system based on standard door hinges now called the Kanellopoulus Track System (KTS). The hinge track system is an inexpensive, all steel, relatively light and easy to build track system. The track is composed of successive bolted together with screws and nylon lock nuts.

Every meter of hinge track can be built within a couple of hours. Every butterfly hinge should be about 1 - 1.3 mm thick and the combined pad, made up from two hinges, 2 - 2.5 mm thick. It requires no building skills - the hinges are simply assembled to the required length. An advantage of this system is that you can easily take out or add one or more hinges, if you want to include a larger wheel or after the track has tensioned.

There are many advantages to the hinge track: the track has completely closed, steel pads; this does not allow sticks or pebbles to stick in between the pads. The steel pads do not wear our on hard terrains, and the hinge pivots dig into the ground. The track can be loose and sagging, thus not causing stress to the motors. All in all this is a crude yet realistic and functional system, in lack of better ideas, funds or skills. A 6.5 cm wide track of this type weighs 1.3 kgrs / meter (2.86 lbs. / yard) or 5.8 lbs for a 6 foot long track, with all the screws and nuts on. It weighs between a TTS track (3 lbs for a 6 foot long track) and a roller chain track (10 lbs per track). In a light or medium vehicle, every hinge track's weight would be about 4 lbs, and with a 50 mm wide hinge, only 3.5 lbs.

Every meter / yard of a hinge track costs around 10 Euros or $ 15 , plus the necessary inox nuts and bolts.

A track system made from chains, nuts and bolts has been developed by Derek Engelhaupt that can be constructed with very few tools and with only a few assembly steps.

These are the parts used to construct my tracks: #50 pitch Tsubaki nickel plated hollow-pin roller chain, 3/16" high-temp rubber fuel hose, 4.5" 10-24 flathead machine screws, and 10-24 nylon insert locknuts.

Performance

As of March 2008, they have yet to be tested in battle, but hopefully the stiffness of the suspension springs (had to be pretty hard in the front and rear of the tank) and the track tensioner will keep them rolling straight and true. There is very little side to side deflection of the track and that is why there are no guide teeth. Time will tell if they will have to be added later.

Based on the wide range of techniques, materials, skills and money that can be used to build an effective R/C track system, one conclusion is painfully clear: you can't draw any conclusions. Personal preferences, your own sense of what's right and shared experiences play a larger role in the selection of a track system, then any scientific or consumer-oriented comparison. Only after dozens of battles have been waged, by a wide range of commanders, will we be able to determine the course(s) that technical evolution takes. But one thing is clear: if you don't build a tracked vehicle and take it into battle, you'll never experience the fun of watching it roll into glory.