Kubota Hydraulic Excavator Thumb Attachment Kit

Runser Custom Machining

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Compatible models 

• Kubota KX71-2, KX91-2, KX121-2 (base mount required) 

• Kubota KX71-3, KX91-3, KX121-3, KX033-4, KX040-4, U35

• Fits Kubota OEM and TAG bucket system.

•  Optional Cylinder base mount (Welding Required) 

• See our common questions page if you are unsure of what your machine requires.  

RCM policies

• Made in the USA 

• 1 year warranty 

• 30 - Day returns 

• UPS Ground shipping 3 - 5 business days  

• Free shipping to the lower 48 states

• Ships to the USA and Canada contact us with your address for an accurate quote.  

• Shipping to Canada, Alaska, and Hawaii, approximately additional ($300 - $450) 

Kit Includes

•  RCM custom designed thumb

• Custom hydraulic cylinder

• Two ½’’ hydraulic hoses 

• Main pin 4140 Heat Treated (not center drilled)

• Two hydraulic cylinder pins

• Two 90- degree elbows 

• Four nuts and bolts 

• Optional cylinder base mount available (welding required).

Thumb Technical Specifications

• Material: Composed of two 3⁄4'' thick AR400 steel tines.

• AR400 is a much stronger and harder steel than A36 steel. Many fabricators only use A36 Steel, causing them to wear down quickly.

• Custom designed and manufactured in the USA. 

• Length = 27’’ 

• Width between thumb bushings (at main pin attachment point) = 10.375’’

• Bucket/coupler width is 10.375”.

• Designed for maximum possible stroke, the thumb folds up and out of the way when not in use, under 12’’. Less than even factory designed models.

• Interference on a 12’’ bucket, thumb will close down to within 2 or 3 inches of bucket teeth. 

Hydraulic Cylinder Specifications

• Cylinder stroke distance = 19’’

• High quality with a stronger internal rod to prevent bending. 

• Made for 3500 psi, tested at 3000 psi. 

• Utilizing side ports allows for the hoses to connect out of the way of use. 

• Custom designed and manufactured in the USA.

Pin Technical Specifications

• The main pin is from 4140 Heat treated, high strength steel. 

• This high strength pin will last, decreasing chances of: complications, breaks, wear, and tear. Not center drilled.

• Due to increased chances of the main pin breaking, we do not center drill the main pins for grease fittings.

Grease Fittings 

• Grease fittings are provided at all pivoting locations. Fittings are protected from material collision that may occur during use. 

• We recommend adding a grease point on the stick of your machine. See our FAQ page for more information 

Key features

• Heavy duty, superior quality, incredible design, and durability.

• Easy Installation 

• Easy customizations to fit your excavator thumb kits needs

• Complete thumb kit with everything you need, to install on your excavator.

• We are continually striving to produce the best quality thumbs possible. 

• These excavator thumb kits are made to last!

RCM is a family owned and run business; we have been producing thumbs in the USA for over 15 years. Due to our designs, fabrication quality, and customer service, we have many happy customers. Check out our reviews. 

For deals or promotions check us out at Runsercm com  If you are interested in a thumb for a different machine or have any other questions; contact us (Jason) email Runsercm @ gmail com call/text twozero8 53nine 93two1.

We will be here if you need us,

Runser Custom Machining