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Installing the counterweight is one of the final operations on a Caterpillar wheel loader assembly line, and one of the most safety-critical.
Depending on the machine model, the cast or fabricated counterweight weighs between 500 kg and more than 5 tonnes. It is secured using 4 to 8 high-strength bolts that must be tightened with extreme accuracy to ensure the required clamp load.
Loose counterweight bolts can result in catastrophic failures, making this a fully traceable, quality-controlled tightening process.
To automate this critical assembly operation, Ansomat engineered a complete high-torque fastening solution using a Stanley Assembly Technologies electronic nutrunner, an integrated torque reaction system, and the Ansomat Traceability Software for complete process control.
Counterweight bolts typically range from M20 to M36, Property Class 10.9 (occasionally 12.9), and require tightening torques from 570 Nm up to nearly 4,000 Nm.
Typical tightening specifications include:
| Botl | Target Torque |
| M20 | 570–650 Nm |
| M24 | 1,000–1,150 Nm |
| M30 | 2,000–2,250 Nm |
| M36 | 3,500–3,900 Nm |
Besides generating extremely high torque, manufacturers must guarantee:
Traditional pneumatic tools offer limited process feedback and cannot provide the digital traceability required for modern Industry 5.0 production environments.
Ansomat delivered a complete ergonomic workstation combining intelligent fastening technology with integrated quality assurance.
The solution consists of:
Unlike conventional high-torque tooling, all torque reaction forces are absorbed by the integrated torque tube and crane structure.
This eliminates the need for a separate torque arm or reaction bar on the tool itself, significantly improving operator ergonomics, accessibility and workplace safety.
Because the counterweight must be seated evenly against the machine frame, bolts are tightened in a controlled crossing pattern instead of sequentially around the flange.
The tightening process consists of three stages.
Each bolt is tightened to approximately 30% of final torque to seat the counterweight correctly.
The bolts are tightened to approximately 70% of final torque to equalize the clamping forces.
Depending on the application, Caterpillar uses one of two advanced tightening strategies.
The electronic nutrunner applies the specified torque while continuously monitoring the tightening angle.
The torque-angle tool immediately detects abnormal tightening behaviour caused by:
For the highest safety-critical joints, the process switches to angle-controlled tightening.
The joint is first tightened to a defined threshold torque before the bolt is rotated through a specified angle.
Compared to conventional torque tightening, this method significantly reduces clamp load variation and delivers much more consistent bolt preload.
Every tightening cycle is continuously analysed.
The integrated calibrated transducer inside the electronic DC tool captures:
Advanced torque monitoring automatically detects:
Machine capability is validated at Cm/Cmk ≥ 1.67, ensuring the fastening process consistently meets Caterpillar's production requirements.
Every tightening result is automatically linked to the individual machine serial number using the Ansomat Digital Work Instructions Software.
Production data includes:
When an NOK result is detected, the software automatically initiates a controlled rework procedure, ensuring defective joints cannot continue through production unnoticed.
The complete digital history remains available for years, supporting quality assurance, warranty investigations and regulatory compliance.
| Before | After with Ansomat |
| Manual high-torque tightening | Automated tightening using a 5000 Nm electronic nutrunner |
| External torque arm required | Integrated torque reaction system eliminates separate reaction arms |
| Limited process control | Intelligent torque monitoring for every bolt |
| Difficult access to recessed bolts | Custom long sockets and ergonomic tooling |
| Manual quality documentation | Automatic traceability software linked to machine serial numbers |
| Risk of skipped or double-tightened bolts | Digital bolt count and position verification |
| Operator-dependent tightening | Guided multi-stage tightening strategy |
| Variable clamp load | Controlled torque-angle tightening |
| Limited production insight | Complete torque-angle data logging |
| Higher warranty risk | Fully validated safety-critical fastening process |
The Caterpillar counterweight assembly workstation now delivers:
Ansomat designs complete high-torque fastening solutions for OEMs in off-highway, construction equipment, automotive, aerospace and industrial manufacturing.
Our expertise includes:
Whether you need controlled tightening at 500 Nm or 5,000 Nm, Ansomat delivers complete fastening solutions that combine productivity, ergonomics and 100% quality assurance.
