The "Balance Ballast" of Excavators! A Guide to Counterweight System (Cast Iron Block + Bolts + Vibration Pads): Structure, Selection & Maintenance

I. Understanding the Counterweight

1. Core Structure & Principle

• Cast Iron Counterweight Block: The "weight bearer", made of high-purity cast iron (3-5 tons for a 20-ton excavator) with an anti-rust coating on the surface. During operation, it generates "balance torque" with its own weight to offset the overturning force of the boom and bucket, preventing the body from tipping backward. For example, when lifting 3 tons of materials, a 3-ton counterweight can just balance the pulling force at the front end.

• Mounting Bolts: The "fixing link", made of 8.8-grade / 10.9-grade high-strength alloy steel, capable of withstanding 50-80kN of tension. They firmly lock the counterweight block to the frame to prevent loosening due to vibration.

• Vibration Pads: The "buffer guard", made of rubber or polyurethane (5-10mm thick), placed between the counterweight and the frame. They absorb 30%-50% of operational vibrations and prevent rigid collisions from wearing the frame.

2. Importance: No Counterweight = "Unstable Scrap Metal"

• Prevent Tipping: Without a counterweight, the excavator will tip backward even when lifting 1 ton of materials, and may even overturn entirely;

• Ensure Stability: Insufficient counterweight causes shaking during slewing, making it impossible for the bucket to operate accurately;

• Avoid Risks: A falling counterweight block (3-5 tons) may injure personnel or damage equipment, leading to serious consequences.

II. Five Key Precautions for the Counterweight

1. Bolt Rust and Breakage: Rain and humidity cause bolts to rust, reducing their strength by 50%. Rusty bolts are prone to breaking during vibration, leading to shaking, noise, or even falling of the counterweight. Replacing bolts costs USD 68.75 - USD 137.5, and frame repair costs USD 2,750 - USD 5,500;

2. Counterweight Block Impact Deformation: Reversing into concrete piers dents or cracks the counterweight, reducing the balance torque by 20% and making the excavator prone to tipping backward when lifting. Welding repairs or replacing the counterweight block costs USD 687.5 - USD 4,125;

3. Vibration Pad Aging: High temperatures and sun exposure harden and crack vibration pads, transferring vibrations directly to the frame, causing paint peeling and metal fatigue. Replacing vibration pads costs USD 41.25 - USD 110;

4. Unauthorized Modification: Cutting the counterweight to reduce weight or adding iron blocks to increase lifting force damages the balanced design—this may cause tire wear at best, or overturning at worst;

5. Long-Term Slope Operation: Slopes steeper than 15° subject bolts to lateral tension, shortening their service life from 3 years to 1 year and accelerating vibration pad wear.

III. Cost-Effectiveness Comparison of Counterweights from Domestic & Foreign Brands

IV. Maintenance Tips!

1. Check Bolts Weekly: Tighten bolts with a torque wrench (80-120N・m). Remove rust and apply grease; replace damaged bolts with high-strength ones of the same specification;

2. Inspect Counterweight & Vibration Pads Monthly: Repair cracks on the counterweight and replace aged vibration pads to avoid shaking and collision;

3. Prevent Rust on Rainy Days: Wipe off water under the counterweight and touch up peeling anti-rust paint;

4. Avoid Impact & Modification: Check the rear when reversing, install anti-collision rubber strips (costing approximately USD 27.5 - USD 68.75), and never cut the counterweight or add iron blocks;

5. Inspect After Slope Operation: Lay steel plates to level the ground, limit operation time to 1 hour, and check bolts and vibration pads after operation.

V. Summary

The counterweight is the "balance cornerstone" of the excavator. Remember 3 key points: understand its structure (counterweight block + bolts + vibration pads), avoid 5 types of risks (rust, impact, etc.), and follow 5 maintenance steps. Proper counterweight maintenance keeps the excavator stable, ensures smooth operation, and saves money while guaranteeing safety!

   About SPARKLING MACHINERY:

   - Founded in 2013, SPARKLING focuses on high-quality excavator parts across hydraulics, undercarriage, engines and electrical systems. We prioritize stability, precision and continuous service, offering worldwide distribution, tailored solutions and strict QC to help customers reduce cost and increase uptime.

   Get In Touch:

   - Replace your failing ECU confidently. Contact SPARKLING for pricing, lead time, and technical support — restore optimal machine control quickly and reliably.