Clegg Hammer – Surface Impact Testing Device
A practical tool for assessing surface stiffness and strength
The Clegg Hammer is a widely used impact testing device designed to evaluate the strength and stiffness of sports surfaces, including natural turf, soil-based fields, and aggregates.
Used since the 1970s, it remains a reference tool for on-site assessment thanks to its simplicity, reliability, and direct measurement approach. The device is designed in compliance with the ASTM F1702 standard, ensuring consistency in testing procedures and data interpretation.
Recognised for its reliability in sports applications, the Clegg Hammer has been used for decades as a simple and effective way to assess surface behaviour under impact conditions.
Measuring surface response in real conditions
Unlike laboratory-based systems, the Clegg Hammer is used directly on site to capture how a surface reacts to impact. It provides immediate insight into surface stiffness, helping to monitor field conditions, compare areas, or track changes over time.
The measured value, expressed as CIV or g-max, reflects the deceleration of the impact and gives an indication of how the surface absorbs and returns energy.
Key Features
Standard-compliant measurement
Designed in accordance with ASTM F1702
Wide measurement range
CIV / g-max values from 20 to 250
Direct data capture
On-screen display with storage on SD card
Efficient field use
Quick and easy data collection on site
Adapted to operational needs
Optional GPS tracking and mobile application
How it works
The device consists of a cylindrical metal missile equipped with an accelerometer, guided through a vertical tube.
The missile is raised to a fixed height of 45.7 cm and released. Upon impact with the surface, the deceleration is measured and automatically recorded. This value is then displayed and stored for further analysis.
