Mechanism, types, operational applications, and how to choose the right model for your excavator
The forestry grapple for excavators is the go-to attachment for felling, harvesting, and handling timber. Mounted in place of the bucket, it transforms a standard excavator into a high-productivity machine for work in forests, green spaces, and logging sites.
But how exactly does it work? And which model should you choose based on the type of work and the excavator’s class? In this guide, we provide practical answers to both questions.
Structure and operating mechanism
The forestry grapple attaches to the excavator arm via a quick-coupler or standard pin, and is powered by the machine’s auxiliary hydraulic system. Operation is based on a system of articulated arms driven by one or more hydraulic cylinders that generate the clamping force necessary to grasp and hold the log.
- Arm attachment. The grapple is attached using a standard connection (pins and eyelets) or a quick-coupling system. The excavator’s auxiliary hydraulic circuit is connected to the grapple’s fittings via high-pressure hoses.
- Opening and positioning. The operator activates the auxiliary control from the cab: the hydraulic cylinders extend the grapple arms to their maximum opening. The excavator arm positions the grapple around the log or bundle of branches to be handled.
- Closure and grip. The second command closes the arms, generating a gripping force on the material. The grapple’s teeth or blades penetrate the bark, ensuring a firm grip even on wet or irregularly shaped logs.
- Rotation (on rotary models). Grabs equipped with a 360° continuous swivel joint allow the material to be rotated once gripped, so that it can be properly positioned during unloading onto a truck or during delimbing operations.
Batch-processing gripper vs. accumulator gripper: which one to choose
There are two main types of forestry grapples for excavators, designed for different stages of the timber supply chain.
| Feature | Blast chiller tongs | Accumulator clamp |
|---|---|---|
| Main function | Felling and Trunk Cutting | Log collection and handling |
| Cutting system | Integrated chain saw | Absent |
| Operational use | Pruning and debudding while standing | Post-treatment loading and storage |
| Gripping capacity | High clamping force to keep the log stable | Wide opening for handling multiple drums at once |
| Compatible excavators | 12 tons and up | 6 tons and up |
| Ideal setting | Dense forests and selective logging | Areas already cleared and intensive harvesting |
| Main advantage | Precision and control during cutting | Maximum productivity during harvest |
The choice between the two depends on the primary operational phase. For those performing the entire cycle (felling + collection + loading), some job sites require the use of both types on different machines. For simpler operations such as slope clearing or urban landscaping, the grapple is generally sufficient.
Operational applications in the forestry sector
Forestry grapples for excavators are used in a wide variety of applications, far beyond traditional logging.
| Application | Type of clamp | Operational Notes |
|---|---|---|
| Selective logging in the forest | Log splitter with saw | Precision cutting to prevent damage to adjacent trees |
| Timber harvesting and loading | Accumulator | Wide opening for multiple drums per cycle |
| Post-storm cleanup | Bucket / Grapple | I work with diverse and tangled materials |
| Maintenance of road embankments | Compact storage unit | Compatible with 6–10-ton mini-excavators |
| Urban Green Space Management | Rotary accumulator | 360° rotation for precision in tight spaces |
| Delimbing | Comb-style hair clipper | Integrated de-stemming comb for cleaning the stems |
Table 1 — Main applications of forestry grapples for excavators.
How to match the grapple to the excavator’s class
The correct match between the grapple and the excavator is essential for operational safety and to achieve optimal performance. There are three parameters to check: the weight of the grapple relative to the excavator’s operating weight, the available auxiliary hydraulic flow (liters/min), and the operating pressure (bar).
A rule of thumb for pairing. The weight of the forestry grapple should not exceed 6–8% of the excavator’s operating weight. For a 20-ton excavator, the ideal grapple weighs between 1,200 and 1,600 kg. Exceeding this limit reduces stability and operational safety, especially on sloped terrain.
As for the hydraulics, most forestry grapples require an auxiliary flow of 80 to 200 liters per minute with operating pressures of 250–350 bar. Before purchasing, it is always advisable to compare these values with the auxiliary circuit specifications listed in the excavator manual.
CMB forestry grapples
CMB Attachments manufactures forestry grapples for excavators suitable for a wide range of applications, from mini-excavators for urban landscaping to professional forestry machinery. The Hardox steel construction ensures wear resistance in the most demanding operating conditions, with 100% testing prior to delivery.
Frequently Asked Questions About Forestry Grabs for Excavators
Can I mount a forestry grapple on a mini-excavator?
Yes, there are compact forestry grapples designed for mini-excavators weighing 3 to 10 tons, which are widely used in urban landscaping and roadside slope maintenance. It is essential to verify the compatibility of the auxiliary hydraulic system: mini-excavators have more limited flow rates, so the grapple must be selected based on the machine’s actual specifications.
Does the forestry grapple work on sloped terrain?
Yes, but you need to consider the weight of the equipment in relation to the excavator’s stability. On slopes steeper than 20–25%, it is advisable to use excavators equipped with leveling or stabilization systems, and to choose grapples that fall within the recommended weight limits for the machine’s class.
What is the difference between a forestry grapple and a Sorting Grab?
The forestry grapple is optimized for gripping logs and cylindrical woody material, featuring contoured arms and penetrating teeth. The Sorting Grab, on the other hand, is designed for mixed materials (scrap metal, debris, bulky waste) and has a wider opening. The two types are not interchangeable.
How much does it cost to maintain a forestry grapple?
Routine maintenance is limited to periodically lubricating the pins (every 8–10 operating hours) and inspecting the hydraulic hoses. With regular maintenance and the use of genuine replacement parts, a high-quality forestry grapple can last for over 5,000 operating hours.
Which forestry grapple is right for you? The CMB team can help you choose the right model based on your excavator, the type of work, and the operating terrain. Contact us for a no-obligation assessment, or explore the CMB Forestry range.