An essential component of the track undercarriage, the JNA0224 chain tensioner assembly by NEXGEN. Designed for 11-15 ton class excavators, including popular JCB models (JS110, JS120, JS130, JS145), Case (CX130), and Sumitomo (SH120-5). This key assembly is responsible for maintaining the correct track chain tension. It consists of a durable cylinder, a heavy-duty spring, and a piston with a grease fitting, which together absorb shocks and prevent the track from derailing or wearing excessively.
In the construction industry, machine reliability is the key to success. That's why we offer high-quality NEXGEN replacement parts for construction machinery, which meet the highest standards of durability and performance. Our products are the ideal solution for companies and specialists looking for reliable components at attractive prices.
| Brand | Type / Series / Model |
|---|---|
| JCB | JS Excavators: JS110, JS120, JS120L, JS130, JS130 AUTO, JS140, JS140 UPGRADE, JS145, JS145 AUTO, JZ140 |
| Case | CX130, JS130, JS140 |
| Sumitomo | SH120-5 |
The list above is for reference only. If you are unsure about the part's compatibility, please contact our experts.
For a complete undercarriage overhaul, we recommend inspecting the condition of the idlers, which work directly with the tensioner, as well as the track chains, track rollers, and sprockets.
Operating with a faulty tensioner (e.g., seized or leaking) is extremely dangerous. It can lead to the track derailing during operation or travel, which risks machine rollover. A chain that is too tight will destroy the chain and sprocket, while a chain that is too loose will destroy the rollers and idler.
The track tensioner is a hydraulic cylinder combined with a heavy-duty spring, mounted in the track frame (between the frame and the idler). Its job is to push the idler wheel forward to keep the track chain under constant, correct tension. This mechanism is tensioned with grease (via a grease fitting) and compensates for undercarriage wear while absorbing harsh impacts.
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No. This tensioner (JNA0224) is for 11-15 ton class machines (like JS130, JS145, CX130). A JS200 is a 20-ton machine and requires a much larger, stronger tensioner.
It is a hydraulic cylinder filled with grease (via a grease fitting) that pushes a piston. The piston presses against the idler yoke, pushing the idler wheel out and tensioning the chain. A large spring inside the cylinder also acts as a shock absorber, absorbing impacts and maintaining tension.
The correct tension (sag) should be checked daily before starting work. It should be adjusted based on conditions: the chain should be looser for work in mud, snow, or soft ground, and slightly tighter for work on hard, flat ground.
Do you have doubts or need confirmation to avoid costly downtime? Call us. Our experts will help you select the right part to get your equipment back to work as quickly as possible.
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Chain tensioner suitable for JCB JS110-130 excavators

















