I. Track tension that’s too tight damages the undercarriage First, let’s talk about what happens when the track is over-tightened.

When an excavator is traveling, the track is not always a perfect circle. When it hits rocks or hard soil lumps, part of the track gets pushed upward, forming a temporary bulge.

If the track is slightly loose: the bulging section has room to flex upward, and the stone passes through without issue.

If the track is too tight: there is no flexibility. The stone forces its way up, and the full tension is instantly transferred to the track  rollers, carrier rollers, idler, sprocket, and track links with bushings.

How big is this force? For a 20-ton excavator, the impact load during travel can reach dozens of tons. A tight track means this impact force is directly and repeatedly imposed on every roller and pin/bushing.

Consequences:

Track rollers and carrier rollers develop internal bearing wear prematurely, resulting in knocking noises during travel.

Track pins and bushings elongate and wear unevenly, increasing pitch and eventually causing climbing or derailment.

Sprocket and track link engagement surfaces wear abnormally, with tooth tips becoming knife-like.

A set of original undercarriage parts worth thousands of dollars can lose at least one-third of its service life due to over-tightening.

II. A slightly loose track brings unexpected benefits

Experienced operators often run tracks that look slightly “slack,” especially in the middle section between the rollers. This is intentional, not negligence.

Benefit 1: Shock absorption

As mentioned above, a looser track absorbs ground impact. When a stone pushes upward, the track deforms locally and absorbs the force, preventing it from being transmitted to the rollers and pins.

Benefit 2: Prevents stone jamming

A tight track has small gaps between links, making it easy for stones to get stuck and compacted, eventually deforming the track. A slightly loose track allows debris to fall out as the track group moves.

Benefit 3: Fuel saving

A tight track increases rolling resistance, like an overly tight bicycle chain. Proper slack reduces resistance and therefore lowers fuel consumption.

III. Golden standard: how loose is correct?

Not too loose, not too tight. Experienced operators use a simple field method—no measuring tools needed.

Measurement position:

Park the machine on level ground. The section between the idler and sprocket is where the track is naturally the loosest.

Method:

Place a straight wooden bar or steel rod across the top of the track between the carrier roller and bottom roller as a reference line. Then measure the vertical distance from this line to the lowest point of the track sag.

Reference values (field experience):

15–20 ton excavator: 30–50 mm sag (about three fingers)

20–30 ton excavator: 40–60 mm sag (about four fingers)

Above 30 tons: refer to manufacturer manual, usually not more than 70 mm

Adjustments by working conditions:

Soft soil/sand: slightly looser to reduce mud packing and derailment risk

Rocky ground or frequent slopes: slightly tighter, but never like a bowstring

IV. Important safety note when adjusting the tension cylinder

When adjusting track tension, the cylinder assy must be mentioned.

Many people only know how to tighten the track by pumping grease into the cylinder. But when the track is too tight and needs to be released, a critical mistake is often made—directly loosening the grease valve or pressure relief valve.

Remember: the tension cylinder contains a high-pressure spring system storing several tons of force. If disassembled incorrectly, the grease fitting can eject like a bullet and cause serious injury.

Correct procedure for releasing tension:

First remove only the external grease fitting (do NOT touch the valve body).

Use a thin steel wire or proper pin tool to gently release the internal check valve ball through the grease port.

Grease will slowly discharge. At the same time, use the bucket or a jack to slightly lift the track to assist pressure release.

Once the correct tension is reached, reinstall the grease fitting and clean off excess grease.

It is better to adjust slowly with a few extra grease pumps than to risk safety by forcibly loosening the relief valve.

Contact undercarriage specilalist:s5@red-hill.cn

Whatsapp:+86 186 4976 8960