Adding a thumb to your excavator and bucket or rake can boost your productivity and the versatility of your machine. Thumbs can help your excavator safely and securely grab and hold more material. And Caterpillar makes it easy to find the thumb that’s right for you.

Let’s take a look at the variety of Cat® thumbs that may suit the needs of your worksite and make your excavator more efficient. The two styles of thumbs are based on how it is positioned: manual and hydraulic.



Manual thumbs are static during use. The bucket curls into the thumb to handle material, and the thumb must be manually adjusted by the operator by moving a rigid, stiff link between the thumb and bracket. These do not require hydraulics, which make them a good choice for excavators with no auxiliary hydraulics systems.

Cat® Stiff Link thumbs are manual thumbs, designed with two static working positions at 90 degrees and 105 degrees. Stiff Link thumbs have a closed face design to better hold fine materials, provide better retention of loose material, and prevent material from packing in the frame. The Stiff Link thumb is universally applicable to a cross range of buckets, making them easier to pair to buckets in a mixed fleet, with three tine configurations for multiple applications. They’re designed for ease of installation with a weld-on bracket and can be easily stored during travel by folding against the machine boom.



Hydraulic thumbs are controllable from the cab and move independently of the bucket. They require an auxiliary hydraulics system to function — a control group, boom lines, and stick lines to connect to the thumb attachment. Caterpillar offers three durable types of hydraulic thumb: the Pro Plus, Pro and Utility options.

1. Utility Thumbs 

Utility Thumbs perform well in less demanding tasks, such as moving and piling brush, rocks and light construction debris. These thumbs cover 50% of the bucket’s rotation, but are lighter than the Pro series thumbs in some size classes by up to 43%, giving you better machine stability. These thumbs feature two tine configurations.

2. Pro Thumbs

Pro Thumbs can cover up to 70% of the bucket’s rotation, offering about 20 more degrees of rotation coverage than the Utility Thumb. Pro Thumbs have configurations of 2-6 teeth with serrations and a unique curvature to help your bucket hold more material. Made to last, with teeth constructed of wear-resistant steel, these thumbs can withstand abrasive materials and handle items with ease.

3. Pro Plus Thumbs

Pro Plus Thumbs can match the bucket’s rotation, with load control at all operating limits and positions. These thumbs include extra links to push the thumb farther. This gives the operator precise control with an added 60 to 70 degrees of rotation coverage beyond the capacity of Pro Thumbs. Like the Pro Thumbs, Pro Plus Thumbs also have configurations of 2-6 teeth with serrations and a unique curvature to help your bucket hold more material. This model is more adept at holding materials vertically and with the bucket longer and is well-suited for material handling applications that require high lift and loading high-sided trucks.

Available thumbs may vary based on your region. Contact your Cat dealer to see which thumb is right for your excavator. Want more technical specifications? Download the Cat thumb technical specifications here.


Learn more about the Caterpillar family of hydraulic excavators.

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