The Timberland Group


The DCRC will allow the user to input known physical loads (lifted load) and Derrick dimensions (boom length, boom radius, mast height, sill length) for TIMBERLAND Portable Derricks. DCRC will then quickly calculate all member forces and reactions. DCRC will tell the user if the load chosen to be lifted at the given boom radius and swing angle is acceptable, or if it overloads the Derrick.

The user can also determine the maximum allowable load that can be lifted at a specified boom radius and swing angle. The structural properties of each of the members of your specific Derrick (boom, mast, legs, sills), as purchased originally from TIMBERLAND, must be entered in strict accordance with the dimensions provided in your derrick user manual.

DCRC uses the input load and position data to calculate stress levels in all members and determine if they are within acceptable AISC (American Institutes of Steel Construction) limits or not. If not, DCRC will display a message that the input rated load is too high for the boom position and other input data chose.

To try out the DCRC, call us at 519-537-6262 to obtain a user name and password or register below.

WARNING: This calculator is applicable only to the Timberland Adjustable Stiffleg Derrick with a standard 8-part load line. It is not applicable to any other derrick.

Two Timberland Adjustable Stiffleg Derrick models: ASD17 (17 Ton Capacity) and ASD35 (35 Ton Capacity) are represented by this calculator. The user must exercise caution to specify correctly the model of Timberland Derrick owned or being considered for his or her job. Failure to specify the correct derrick model will result in erroneous results from the calculator, which could create an unsafe condition.

The calculator must be used strictly in accordance with the instructions contained herein. Timberland will not be responsible for any actions resulting from misuse of the calculator.

WARNING: User MUST check BOTH positive and negative boom swing angles and take the worst-case of the two. (I.e. Check BOTH + 120 degrees and – 120 degrees). The calculator includes an assumed mast list angle which WILL provide a different result for each case.


Click here to use the Derrick Capacity & Reaction Calculator (DCRC)