Track Chains- The Steel Backbone of Your Undercarriage System

What Track Chains Are And How They Define Undercarriage Performance

The track chain, also called a track link assembly or digger chain, is the continuous steel loop that forms the structural foundation of the undercarriage system on steel-tracked excavators, bulldozers, and other heavy tracked machinery. It consists of alternating inner and outer link plates connected by hardened steel pins running through hardened steel bushings, with track shoes bolted to the outer link plates to form the ground contact surface.

The track chain performs three functions simultaneously. It transmits the drive force from the sprocket to the ground contact surface, converting the rotational output of the final drive into the linear motion that moves the machine. It distributes the machine's operating weight across the full length of the lower run, spreading the load across every track roller contact point along the way. And it provides the structural loop that keeps every other undercarriage component  rollers, idler, carrier rollers, sprockets  in its correct relative position and running geometry.

Sealed and Lubricated Track Chains Why They Last Significantly Longer

The sealed and lubricated track chain addresses this directly. A sealed and lubricated chain incorporates an internal grease reservoir between each pin and bushing, sealed by a rubber O-ring at each end of the bushing bore. The grease charge lubricates the pin-bushing interface continuously throughout the service life of the chain, reducing the wear rate at the point of highest mechanical stress in the entire track chain system.

The performance difference is significant and consistent across applications:

• In standard mixed-terrain construction conditions — sealed and lubricated track chains typically deliver 30 to 50 percent longer service life than equivalent dry chains
• In highly abrasive conditions — sand, rock aggregate, quarry environments the advantage of sealed lubrication is even greater. The O-ring seals prevent abrasive particles from entering the pin-bushing interface, which is the primary wear accelerator in abrasive operating conditions
• In wet and muddy conditions — sealed chains prevent moisture and fine soil particles from contaminating the pin-bushing interface, maintaining the internal grease charge across operating conditions that would flush or contaminate an unprotected interface rapidly

At Imara Engineering, sealed and lubricated track chains are the specification we recommend for any machine operating in abrasive, wet, or high-debris conditions and they are the specification we stock as the priority option across the most widely operated excavator and bulldozer brands.

Warning Signs, When Your Track Chain Needs Replacing

Track chain wear communicates itself through measurable pitch elongation and through the behaviour of the machine and the components around it. These are the signals that demand attention:

• Track chain pitch elongation beyond the manufacturer wear limit — the definitive replacement signal. Pitch elongation is measured by counting a specific number of links and comparing the measured distance against the new specification. Most manufacturers specify a maximum elongation of 2 to 3 percent of nominal pitch before replacement is required.
• Track sagging excessively between the idler and sprocket despite correct adjuster tension — advanced pitch elongation has stretched the chain beyond the point where the track adjuster travel can compensate. The adjuster is at or near maximum extension and the chain is effectively too long for the undercarriage system.
• Sprocket teeth showing accelerated wear on a recently inspected sprocket — worn track chain pitch is driving the sprocket teeth at an incorrect contact geometry, accelerating sprocket tooth wear beyond the normal rate. The chain and sprocket are destroying each other simultaneously.
• Visible link plate thinning or cracking — advanced wear on the link plates themselves. Plate thinning reduces the structural section of the chain and increases the risk of link plate fracture under peak load conditions.
• Pin rotation — pins turning within the link plates rather than remaining fixed the pin-to-link plate interference fit has failed. A rotating pin accelerates both pin wear and link plate bore wear simultaneously and is a replace-now situation.

• Track shoes loose or require more frequent re-torquing than normal — link plate deformation from advanced wear is allowing the track shoe bolt holes to elongate, reducing the clamping force available for the shoe bolts.

Track Chain Specifications, Getting the Right Assembly for Your Machine

The correct track chain specification is defined by five parameters and a mismatch on pitch or link plate specification produces a chain that either does not engage the sprocket correctly or cannot support the machine's operating weight across its rated service life:

• Track pitch — the centre-to-centre distance between consecutive pin centres. Must match the sprocket tooth spacing exactly. Even a small pitch deviation produces the abnormal sprocket contact that accelerates both chain and sprocket wear simultaneously.
• Link plate width and height — the link plate dimensions determine the structural section of the chain and the track shoe bolt hole pattern. Must match the machine's track shoe specification exactly.
• Pin and bushing diameter and grade — the pin and bushing diameters determine the bearing area available to resist the pin-bushing contact load at each sprocket engagement. Pin and bushing grade surface hardness and core toughness determines service life under the operating loads of your specific machine weight class.
• Number of links — the total link count determines the chain loop length and must match the track frame geometry of your specific machine. An incorrect link count produces a chain that either cannot be tensioned to the correct setting or exceeds the track adjuster travel range.
• Sealed or non-sealed specification — must be confirmed for your specific application. On some machines the track frame and sprocket configuration is specifically designed for sealed chain — fitting a non-sealed chain to a sealed-chain-specification machine produces accelerated wear from the first operating hour.

At Imara Engineering, every track chain order is confirmed against all five parameters using your machine serial number. Provide your machine make, model, and serial number and we confirm the exact track chain assembly specification before your order is placed.

Track Chains by Machine Brand

Our track chain inventory covers the most widely operated excavator and bulldozer brands all cross-referenced against OEM part numbers and all forming part of our broader undercarriage parts range.

Caterpillar Track Chains

Covering the Cat mini excavator range and the Cat bulldozer range from D4 through D9. Cat track chain assemblies are manufactured to the precise pitch, link plate specification, and pin and bushing grade of each Cat model confirmed against Cat OEM part numbers. Sealed and lubricated Cat track chain specifications are stocked across the most widely operated Cat bulldozer and excavator weight classes. Cat D6 and D8 dozer track chains are priority stock specifications.

Komatsu Track Chains

Compatible with the PC series mini and compact excavator range from PC15 through PC78 and larger models including the PC200, and the Komatsu D series bulldozer range from D39 through D155. The Komatsu PC200 track chain assembly is a consistently demanded specification stocked as a priority item. Sealed and lubricated Komatsu track chains are available across the PC200 and D series specifications for operators in abrasive or high-wear operating environments.

Hitachi Track Chains

Stocked for the Hitachi ZX series including ZX35, ZX50, ZX75, and the ZX200. Hitachi track chain assemblies are confirmed against Hitachi OEM part numbers for pitch, link plate specification, and pin and bushing grade across the ZX range. Always specify the ZX model designation ZX200, not PC200  when ordering Hitachi undercarriage parts.

Other Brands

We also stock or can source track chain assemblies for Kubota, Bobcat, JCB, Takeuchi, Doosan, and Volvo excavators and for aftermarket dozer track chains across John Deere, Case, and Liebherr bulldozers. Contact the Imara Engineering team with your machine make, model, and serial number and we will confirm availability.

OEM Quality, What Every Track Chain Assembly Is Built To

Every track chain assembly in our undercarriage parts range is held to four quality standards:

• Track pitch confirmed to OEM specification 
• Pin and bushing surface hardness and core toughness matched to machine weight class 
• Link plate material grade and heat treatment confirmed 
• O-ring seal specification confirmed for sealed and lubricated chains 

OEM track chains carry a brand premium above equivalent quality aftermarket specification. At Imara Engineering, the pitch accuracy, material grade, pin and bushing specification, and fitment guarantee are the same standard. The premium is not.

Track Chains and the Excavator Chains and Sprockets System

The track chain and the drive sprocket are the two halves of the most critical wear couple in the undercarriage system and the decision about when and how to replace them is one of the most consequential maintenance decisions an operator or fleet manager makes:

• Always replace sprockets alongside track chains 
• Always inspect track shoes when replacing the track chain 
• Confirm idler wheel and track adjuster condition

Industries We Supply Track Chains To

• Construction & Civil Engineering — excavator track chains and dozer track chains for machines on active construction programmes. Sealed and lubricated track chains are the specification we recommend for construction site conditions where abrasive aggregate contact significantly accelerates dry chain pin and bushing wear.
• Mining & Quarrying — aftermarket dozer track chains for heavy bulldozers operating in continuous high-load production cycles on abrasive quarry floors. Sealed and lubricated specification and high-grade pin and bushing hardness are non-negotiable for mining dozer track chains.
• Agriculture & Land Management — track chain assemblies for compact excavators and bulldozers operating in wet, high-moisture conditions where sealed chain specification prevents the moisture and soil particle contamination that accelerates dry chain wear in agricultural environments.
• Pipeline & Utility Trenching — digger track chains for excavators working on stony easement corridors. Rock and aggregate contact accelerates pin and bushing wear sealed and lubricated chains are the preferred specification for pipeline and utility trenching applications.
• Plant Hire & Rental Fleets — track chains for sale across mixed-brand hire fleets where consistent quality and reliable lead times define the supplier relationship. Imara Engineering supplies hire operators with trade pricing and serial number verified specifications as standard.