How to Measure Excavator Track Pitch, Bushing Diameter & Roller Flanges: A Technical Selection Guide
April 10, 2026
When replacing worn undercarriage components on your crawler machinery, even a tiny millimeter deviation in dimensional measurements can cause severe pitch mismatch, chain binding, or premature seal failure. While ordering replacement parts using OEM part numbers or machine model codes (e.g., Cat 320, Komatsu PC200) is standard practice, verifying physical dimensions on-site is the ultimate safeguard against costly returns and jobsite downtime.
This technical guide by Shengan Excavator Parts provides a step-by-step walkthrough on how to accurately measure Track Pitch, Bushing Outer Diameters, and Track Roller Flange configurations.
1. How to Measure Track Link Pitch (P) Accurately
The Track Pitch is the center-to-center distance between two consecutive track pins. Over time, internal pin-and-bushing wear causes the track chain to stretch (pitch elongation). Measuring pitch correctly determines whether you need a track tension adjustment or a full track link chain replacement.
Pin Center 1 Pin Center 2
|<------- Pitch (P) ------->|
+-----+ +-----+
| (O) |=====================| (O) | <-- Track Link Rail
+-----+ +-----+
Step-by-Step Measurement:
- Drive the Machine Straight: Park the excavator on flat, solid ground so the upper track section is under normal tension.
- Span Across 4 Pins (Best Practice): Measuring a single link pitch can lead to error due to localized wear. Use a steel tape measure to measure the distance across four consecutive pins (from the leading edge of Pin 1 to the leading edge of Pin 5).
- Calculate Average Pitch: Divide the total measured distance by 4.$$\text{Average Pitch} = \frac{\text{Total Distance across 4 Pins}}{4}$$
- Compare with Standard Pitch Charts:
- PC200 / CAT 320 Class: Standard Pitch = 190 mm (7.48 in)
- PC300 / CAT 330 Class: Standard Pitch = 215.9 mm (8.50 in)
- PC400 Class: Standard Pitch = 228.6 mm (9.00 in)
- If your measured pitch exceeds OEM allowable wear limits (typically >3% stretch), the track link group requires immediate replacement.
2. Measuring Track Bushing Outer Diameter & Pin Bore
The track bushing interfaces directly with the drive sprocket teeth. Worn bushings lead to sprocket tooth jumping and accelerated rail wear.
- Bushing Outer Diameter (OD): Use a digital vernier caliper to measure the OD at the center section (where sprocket engagement occurs) and at the unworn outer edges near the link counterbores. The difference indicates total bushing wall wear.
- Pin Bore Diameter: When replacing bare track links, measure the inner diameter of the link pin bore using an inside micrometer to ensure proper press-fit tolerance during hydraulic pin installation.
3. Identifying Single Flange vs. Double Flange Track Rollers
Installing the wrong roller flange type compromises machine stability and causes uneven track link rail wear. Shengan manufactures both Single Flange (SF) and Double Flange (DF) track rollers engineered with deep induction-hardened treads.
SINGLE FLANGE (SF) DOUBLE FLANGE (DF)
+-------+------+ +----+------+----+
| | Rail | |Rail| |Rail|
|Flange | Tread| |Flange|Tread|Flange|
+-------+------+ +----+------+----+
(Mounted inside/staggered) (Straddles link rails)
| Roller Type | Structural Configuration | Primary Mounting Position | Function & Advantage |
| Single Flange (SF) | Single outer guiding lip along one side of the roller shell | Mounted in staggered positions along the track roller frame | Prevents lateral chain drift while allowing smooth rail passage |
| Double Flange (DF) | Two guiding flanges straddling both sides of the track link rails | Mounted near the idler and sprocket ends of the frame | Provides maximum lateral restraint against track derailment on slopes |
4. Why Dimensional Precision Matters at Shengan
At Shengan Excavator Parts, every Track Link, Track Roller, Carrier Roller, Idler, and Sprocket is manufactured using precision CNC boring and automated heat-treatment processing:
- Zero-Tolerance Pitch Matching: CNC-machined link pin holes guarantee exact pitch alignment, eliminating chain binding.
- 100% Submerged Pressure Testing: Assembled rollers are submerged and pressure-tested to ensure duo-cone mechanical face seals remain 100% leak-proof.
- Custom Engineering Support: If you operate non-standard or older machinery models, send us your caliper measurements or CAD drawings for instant OEM cross-referencing!
Contact our technical sales engineers to request technical specification sheets and direct factory quotes.
