What Is a Driven Track System?

What Is a Driven Track System? Closed-Loop Transport Guide

Author: ShanGong, Engineering Director | Published: September 21, 2026 | Category: FAQ About Circular Motion

In factory automation, a driven track system is a closed-loop guided track on which load-carrying carriages are moved from station to station. The carriages are driven either by one shared mechanical element, such as a timing belt, a chain or a link drive, or individually by linear motor movers. The loop runs continuously or in indexing steps and forms the transfer backbone of a multi-station assembly or inspection cell.

A conveyor moves parts, while a driven track system also positions them, which makes it closer to a conveyor that can act as a positioning table. Picture a twelve-station cell where every carriage has to stop within a few hundredths of a millimetre so that a robot can drive a screw into the part it carries. Whether a driven track system can hold that depends on three decisions: how the carriages are driven, how each station locates them, and how the loop is laid out.

Driven Track System at a Glance

The three building blocks

The track is a loop of hardened rail segments. Straight sections carry most of the working stations, curved sections turn the carriages back on themselves, and every point where a straight meets an arc is a joint that has to be aligned during installation.

The carriages ride on V-profile guide rollers that grip the rail from both sides. That grip lets a carriage take side loads and tipping moments from the process instead of relying on gravity to stay seated. Each carriage carries the fixture that holds the workpiece.

The drive is a motor, a transmission element and the connection between that element and each carriage. That connection is what separates one type of driven track system from another, and it is the subject of most of this page.

Figure 1: Labelled drawing of a short loop showing the rail (straight and curved segments), one track joint, a carriage with its V-guide rollers, and the drive pulley or sprocket. 

How it differs from conveyors, index tables and AGVs

A driven track system keeps the part on a guided carriage for the whole loop, so a station never has to lift a pallet off a moving belt to locate it. It also differs from a single linear module, which moves back and forth and can be in only one place at a time, whereas a loop keeps carriages at every station at once and returns them without a separate return conveyor. Where a pallet line or an index table is the better answer is covered in circular conveyor vs pallet conveyor and circular conveyor vs rotary indexing table.

How a Driven Track System Moves Carriages Around the Loop

Guidance: rolling on straights and arcs

On a straight, the guide rollers see a rail of constant shape. At the entry to an arc, the rail starts to curve under the carriage while the rollers are still spaced for a straight line, so the roller geometry and its eccentric adjustment decide how much play the carriage has as it turns.

Every carriage crosses every joint on every lap, which turns a small step or gap at a straight-to-arc transition into a repeated impact on the rollers and on the part. TallMan holds joint step and gap to 0.03 mm for this reason. A common mistake is to choose the smallest arc radius available to save floor space. A tighter arc turns the carriage through the same angle over a shorter distance, and the lateral acceleration at the transition rises accordingly. Joint alignment is covered in how to ensure a smooth transition at track joints.

Drive engagement: why some linked carriages speed up on the curves

On loops where the belt wraps a pulley that shares its centre with the arc, the belt and the carriage travel around the same centre at different radii: the belt on the pitch radius of the pulley, the carriage further out on the rail. Both turn through the same angle in the same time, so the carriage covers more ground on the arc and moves faster there than on the straight.

Take a pitch radius of 100 mm and a carriage attachment at 130 mm. A carriage running at 1.0 m/s on the straight passes through the arc at 1.3 m/s, speeding up as it enters every curve and slowing down as it leaves. A fixtured rigid part may not notice, but loose components, liquids and tall parts often do, and the repeated speed change then sets the usable line speed. Loops that route the belt around the arc in another way, for instance along a curved belt guide, need their own analysis.

A chain adds a second effect. A sprocket engages the chain like a polygon rather than a circle, so the chain speed pulses slightly once per tooth, known as chordal action, and the pulse is larger on sprockets with fewer teeth. A train of carriages joined by rigid links keeps its spacing fixed, but each link entering the curve meets the same chord-versus-arc geometry, so constant speed should not be assumed for it either. Carriage speed stays the same through the arc only when the attachment point sits on the pitch line of the drive at that arc.

When comparing systems, ask the supplier where the carriage attaches relative to the drive pitch line on the arcs. Whether a line should then slow down through its curves is answered in does the running speed of arc segments need to be reduced.

Figure 2: Plan view of one arc showing the belt pitch radius and the carriage attachment radius, with velocity arrows of different length on the straight and on the arc. 

Continuous motion vs indexing

In continuous motion, the carriages never stop. That suits processes that can work on a moving part, such as coding and printing, vision inspection with encoder tracking, curing, cooling and accumulation.

In indexing motion, the carriages move, stop while the stations work, and move again, as assembly, screwdriving, pressing and dispensing usually require. One index cycle adds up acceleration, travel, deceleration, the settling time while the carriage is located, and the process time. On short index moves the carriage spends most of the move accelerating and decelerating, so average speed decides the cycle time far more than the top speed on a data sheet. A heavier fixture also lowers the acceleration the drive can deliver, which is why payload should be fixed first and speed checked against it afterwards. When carriages are linked, they all stop together, so the slowest station sets the dwell for every station. Working through the numbers for a specific line is covered in conveyor cycle time calculation.

Figure 3: Timeline of one index cycle with segments for accelerate, travel, decelerate, locate and process, marking the slowest station as the one that sets the dwell.

That shared stop follows directly from how the carriages are connected, and the connection divides driven track systems into two families.

Two Families: Linked Carriages vs Independent Movers

Mechanically linked systems

In a linked carriage track system, every carriage is tied to the same transmission element, which may be a timing belt, a chain, a link drive or a screw-type drive, and one motor moves them all. Carriage pitch is fixed when the system is built, and every carriage covers the same distance in the same time, so the loop runs at the rhythm of its slowest station. This page concentrates on this family, in belt, chain and link drive.

Linear motor movers

In a linear motor track, the track sections carry the coils and each mover carries permanent magnets, so every mover has its own position loop and can be sent anywhere independently. Pitch becomes a software setting, and a slow station can be doubled so that two movers are worked on in parallel. A mover generally accepts less payload and side force than a carriage on a heavy rail, and the controls, encoders and programming grow with the length of the track. The full comparison is in circular conveyor vs linear motor conveyor.

A quick decision rule

Independent movers are worth considering when:

• the product changes often and the pitch changes with it
• station times differ widely and the slow stations need to run in parallel
• the loop has to buffer parts between processes running at different rates

Linked carriages usually fit better when:

• every station runs to the same cycle and the pitch stays fixed for the life of the product
• the cell produces dust, oil, coolant or heat that electronics along the track would have to tolerate
• each carriage carries a heavy fixture or takes large process forces, such as pressing

Belt, Chain or Link Drive: What Changes in Practice

The table compares the drive element only. The guide rails need lubricating whichever drive is chosen, and the accuracy row assumes a positioning mechanism at the station, as explained further down.

When belt drive fits

The limitation comes first: under acceleration, a timing belt stretches a little between the pulley and the carriage, so the belt alone gives a coarse position, and stations that need precision add a positioning mechanism. In return, the belt runs quietly and needs no lubricant on the drive, which suits electronics assembly and clean packaging areas with light to medium payloads. The belt range starts with the belt drive oval circular conveyor.

When chain drive fits

Over the life of a chain, the variable that matters is elongation. The pins and bushings wear, pitch grows, and a tensioner takes up the slack. For general industrial drives about 3 percent elongation is the common replacement limit, tightening to around 1.5 percent where smooth running or fixed centres matter (Reliable Plant), and some chain makers set 2 percent (Renold). A driven track depends on carriage pitch for positioning, so the tighter end of that range is the safer reference. With that wear managed, a chain gives the stiffness that heavier fixtures need, and it is the drive behind the ±0.03 mm tier. See the chain drive oval circular conveyor, and for a head-to-head comparison, belt vs chain drive circular conveyor.

When a link drive fits

Here the carriages are not attached to a belt or chain at all. In a link drive, sometimes called a connecting rod drive, the carriages are joined to each other by rigid links and move as one closed train. With no flexible element between neighbours, the spacing cannot drift over the service life, and the carriage count is fixed when the system is built. TallMan link drive systems carry up to 15 kg per carriage, and their accuracy is specified per application against the station requirements. The design is described on the link drive circular conveyor page.

Where Positioning Accuracy Really Comes From

Drive stiffness sets the coarse position

The servo encoder measures the motor shaft, not the carriage. Between the two sits a belt that stretches, or a chain with backlash and slowly growing pitch, so the motor can be exactly where it was told to be while the carriage is not. The drive brings a carriage close to its station, and something else has to finish the job. The factors involved are covered in what affects the positioning accuracy of a circular track conveyor.

The station positioning mechanism sets the fine position

At a precision station, a positioning mechanism takes over once the servo has brought the carriage close. Because the carriage is connected to the belt or chain through a floating joint, the mechanism can pull it into an absolute position without fighting the drive, at every stop. The two mechanisms TallMan uses do different amounts of work:

• Pneumatic rod mechanism. A cylinder drives a rod into a bush on the carriage and locates it in two axes, along the track and radially, so the accuracy figure applies in both directions.
• Cylinder stop. A cylinder presses against a flat face on the carriage and locates it along the track only. The radial position is left to the guideway.

A station that needs a hole position in both directions, such as screwdriving or pin insertion, calls for the rod mechanism. A station that only needs the carriage stopped at the right point along the track, such as a label or a pass-through vision check, can use the stop. The split between coarse and fine positioning is described on a ring guide track conveyor project.

Consider a screwdriving station that needs each screw hole within ±0.05 mm of where the robot expects it. Belt stretch under acceleration depends on the load each carriage carries, so when fixtures are loaded differently, the stop position shifts from one carriage to the next. A locating rod removes that variable, because the carriage ends up where the bush puts it, whatever the belt did on the way in.

Accuracy tiers by drive type

Repeat positioning accuracy depends on two things together: the drive type and whether the station has a positioning mechanism. With a positioning mechanism, a chain drive reaches ±0.03 mm and a timing belt drive reaches ±0.05 mm. Without one, the carriage position is held to about ±0.5 mm. For the link drive, accuracy is specified per application.

When comparing quoted figures, ask whether each one assumes a positioning mechanism, and in how many axes. A figure with one and a figure without one describe different systems, even on the same driven track system.

If you already know which stations need a locating mechanism, send a sketch of the loop with the tolerance each station needs, and our engineers will tell you which tier each drive option falls into: Request a Quote — Circular Conveyor System.

Loop Shapes, Carriage Pitch and Mounting Orientation

Oval, rectangular, round and custom loops

An oval loop has two straights joined by two 180° arcs and is the most compact way to return carriages. A rectangular loop has four straights and four 90° corners, which gives station space on all four sides at the cost of more joints. A round loop is a single constant-radius ring, usually driven through a toothed ring, with no straight-to-arc transitions at all. Custom shapes follow the layout of an existing machine. As a rule of thumb, long narrow floor space suits an oval, while squarer space, or process equipment that has to sit inside the loop, suits a rectangle. All four appear in the circular track system range.

Figure 4: Four loop shapes side by side (oval, rectangular, round, custom) with station positions marked. 

The pitch rule

On a linked system, the carriage count multiplied by the carriage pitch equals the loop length, and the pitch has to be a whole number of teeth or links on the drive element. For example, a belt with 400 teeth at a 10 mm tooth pitch gives a 4,000 mm loop. Sixteen carriages divide it into 25 teeth each and can be built. Fifteen would need 26.67 teeth each, so either the carriage count or the belt has to change. Round loops driven through a toothed ring follow the same logic, since the station count must divide the tooth count exactly for the mesh to repeat at every station.

The common mistake is to fix the station count first and choose the loop afterwards, only to find that the pitch does not land on a tooth. Sizing a loop from all its constraints at once is covered in how to determine the diameter of a circular conveyor.

Horizontal vs vertical installation

Standing a loop on its edge saves floor space but changes the loads. On a vertical loop, carriages on the lower run hang from their rollers, so the load direction on the rollers reverses once per lap. When carriages are unevenly loaded, gravity on the rising and falling sides no longer balances, and the drive has to hold the difference. A brake motor, together with protection against a belt or chain break so that the train cannot run away, is part of the design rather than an option. More is on the vertical circular conveyor system page.

What the mounting frame has to hold

The track can only be as accurate as the frame under it. TallMan asks for the customer mounting frame to be flat within ±0.15 mm over any 3 m and ±0.3 mm over any 10 m. On twin-rail loops, the joints of the two rails are staggered so that a carriage never crosses both joints at the same moment.

Where Driven Track Systems Are Used

Assembly is where indexing and positioning mechanisms matter most, because screwdriving, pressing and insertion all need the carriage held still and located while the tool works. The same pattern runs from automotive components, where carriages index through bolt tightening and leak testing, to closure assembly, as on a multi-station line assembling 55 mm non-spill bottle closures.

Medical devices and food packaging add cleaning and corrosion to the brief. A syringe or test-kit line indexes nests through filling, insertion and inspection, while a food line carries cartons through filling, sealing and labelling. Where washdown or corrosive cleaning is involved, a 316 stainless guideway is available, with load and life ratings specified per application.

Inspection and testing can use either motion mode. The deciding question is usually how each result is tied back to a specific carriage. With continuous motion, the camera trigger comes from the encoder position of the carriage. With indexing, the part is stationary but the station has to read the carriage identity at every stop. See integrating a visual inspection system into a circular conveyor.

Buffering uses the loop as storage between two processes running at different rates, holding parts on carriages until the downstream machine is ready, as on cosmetic compact packaging lines.

“High Speed Driven Track System from TallMan Robotics Limited”,

TallMan Driven Track System Range at a Glance

For readers who want to check a requirement against what is built as standard, the main limits of the TallMan linked-carriage range are:

• Drives: timing belt, chain and link drive, with round loops driven through toothed arc rails.
• Guideway widths: 23, 25, 28, 30, 44 and 50 mm, in V-profile and T-profile rails.
• Standard arc diameters: from 200 mm up to 1,000 mm. Project lines have used ring rails of 2,400 and 3,500 mm for heavy round tracks.
• Repeat positioning accuracy: ±0.03 mm (chain) and ±0.05 mm (belt) with a positioning mechanism, and ±0.5 mm without one.
• Positioning mechanisms: pneumatic rod (two axes) and cylinder stop (one axis).
• Link drive payload: up to 15 kg per carriage.
• Materials: a 316 stainless guideway option for washdown and corrosive cleaning.
• Lubrication: manual application or felt lubrication devices, with an automatic pump unit that removes the periodic task.

Model codes and the full parameter tables are in the circular conveyor catalogue and datasheets.

What to Prepare Before You Specify a Driven Track System

Each item below changes the design in a specific way, and a proposal built without one of them usually has to be revised later.

1. Loop shape and outside dimensions. These set the frame, the arc count and the available straight length.
2. Number of stations and their spacing. Together these set the carriage pitch, which then has to pass the pitch rule.
3. Payload per carriage, including the fixture, and its centre of gravity. These size the rail, the rollers and the drive, and they come before speed.
4. Cycle time and index distance. This decides the motion profile, and whether the average speed over a short index can meet it.
5. Accuracy needed at each station, and in which axes. This decides which stations need a positioning mechanism, and which type.
6. Mounting orientation. A vertical loop needs brake and break protection.
7. Environment: dust, washdown, cleanroom class or temperature. This affects materials, seals and lubrication.
8. Interface to the PLC or robots. This covers where the sensors sit and how each carriage is identified.

An oval line built for a customer in Thailand shows why the list matters. During design, the number of positioning stations grew from two to eight, and the customer then asked for the drive motor to be moved. The new motor position interfered with the existing base plate fixing holes, which had to be corrected before the final 3D model could be confirmed. None of these changes was difficult on its own, but each one travelled through the rest of the design, and settling the list at the start avoids that loop.

With the eight items to hand, Request a Quote — Circular Conveyor System. Send what you have, and our engineers will point out which inputs are still missing before sizing anything.

Driven Track System FAQ

Is a driven track system the same as a circular conveyor?

The two overlap heavily but are not identical. “Circular conveyor” usually refers to linked-carriage loops driven by belt, chain or link drive, which are the systems this page concentrates on. “Driven track system” is the broader term and also covers loops with independent linear motor movers. See circular conveyor systems.

Driven track system vs AGV: which should I choose?

An AGV wins when routes change or differ from one unit to the next. A driven track system wins when the sequence is fixed and every station needs the same repeatable stop, because a fixed track does not navigate and so gives the same cycle every time. In a high-frequency, fixed-sequence cell, the flexibility of an AGV often goes unused.

Why do carriages speed up on the curves of some track systems?

When a carriage is attached further out than the pitch line of the drive around the arc, it covers more ground per revolution than the belt does, so it moves faster there. The effect grows with the difference between the two radii. The drive engagement section above works through an example.

Can a driven track system be mounted vertically?

Yes. A vertical loop needs a brake motor and protection against a belt or chain break, and the carriage load has to be checked on both the upper and lower runs, because the load on the guide rollers reverses between them.

How many carriages can one driven track loop carry?

Divide the loop length by the carriage pitch. The pitch must be a whole number of belt teeth or chain links, and it cannot be shorter than the carriage length plus the clearance each carriage needs through the arcs. The pitch rule section includes a worked example.

What happens if a carriage jams on the track?

On a linked system, one jammed carriage stops the whole loop, so the driving force needs a cap below what would bend a fixture or the drive. That cap comes from an overload release or torque-limiting device, combined with motor current monitoring. Ask which protection is fitted and whether it resets automatically.

How often does a driven track system need lubrication?

This depends on the lubricant. A spray-type penetrating lubricant needs reapplying every 3 to 5 days, and ISO VG 46 class guideway oil about every two weeks, while solid grease allows long intervals with little routine attention. The intervals are the same whether the lubricant is applied directly or through a felt device. Only an automatic pump unit removes the task.

What does the mounting frame need to provide?

Flatness. TallMan specifies ±0.15 mm over any 3 m and ±0.3 mm over any 10 m for the customer frame, because rail accuracy cannot be better than the surface the rail is bolted to.

Can the loop be extended or rearranged later?

Straights can usually be lengthened while the arcs are reused, but a longer loop needs a longer belt or chain and a carriage count that still satisfies the pitch rule. If an extension is likely, plan the pitch and frame for it at the design stage.

Choosing the Right Driven Track System

A driven track system is chosen in three steps. First, decide whether the carriages should be linked or independent. Next, choose the drive that suits the load and the environment. Then add positioning mechanisms at the stations that need precision, and size the loop so that the carriage pitch lands on a whole tooth or link.

If you have the eight inputs listed above, Request a Quote — Circular Conveyor System and our engineers will come back with a proposed layout.