DTOC® takes the guesswork out of well service operations

DTOC® takes the guesswork out of well service operations


Oil well service operators play a critical role in pumping and cementing operations, but they aren’t always given the controls to do the job precisely. And precision is a must when running a massive hydraulic fracturing or cementing trailer. Now, operators can perform their duties with much more exactness using Caterpillar’s Dynamic Transmission Output Control (DTOC) technology. DTOC is the answer to well service operations that typically have to be done by feel, as it provides much needed automation for tasks that typically require a lot of input from the operator.

How it works

Caterpillar’s DTOC technology is compatible with all current generation pressure pumping transmissions, as well as our smaller CX31 and CX38 well service transmissions. It requires no additional hardware, as is purely a software-based solution.  DTOC can be integrated into nearly any 3rd party control system and is intuitively easy to manage for any experienced well service operator.


Compatible with all current generation pressure pumping transmissions, Caterpillar’s new DTOC technology provides much needed automation for tasks that typically require a lot of input from well service operators

DTOC offers several functions, and automation is the unifying theme. These functions include Automated Stall Test Mode (ASTM), Automated Speed Control (ASC) and Economy Mode. Here’s a brief snapshot of how each feature works:


  • Automated Stall Test Mode – Before pumping a job on a well, it’s necessary to pressure test the hydraulic iron leading to the well to ensure there are no leaks.  This pressure test operation is typically a manual process controlled by the operator.  ASTM is a transmission control feature designed to automate the pressure-test operation.  ASTM simplifies the process for the operator by allowing them to simply enter the desired pressure into their control screen, and activate the feature.  Once ASTM is activated, the transmission controller takes over and controls transmission gear and engine speed to achieve the desired pressure, and exit to either P or N.  ASTM is designed specifically to provide a safe and controllable pressure-test operation, with accurate pressure-test results.

  • Automated Speed Control – Automated Speed Control (ASC) is a feature designed to automate pump rate control during normal pumping operation.  On today’s well service pumping equipment, pump flow is controlled by commanding engine speed and selecting the gear that provides a flow rate nearest to your target flow rate.  Each transmission gear shift can significantly increase pump flow, and potentially pressure.  With Automated Speed Control, we’ve provided a rate-control feature that simplifies the pump control by allowing the operator to simply dial in the desired flow rate.  ASC commands engine speed while also selecting the appropriate gear to achieve and maintain the desired flow. 

    While in ASC mode, the transmission will automatically shift gears as necessary, and will control the gear shift and engine speed in order to maintain the desired rate before and after the shift, ensuring there are no flow spikes during gear shifts.  On a multi-rig controller, ASC could be integrated to command rate control to an entire pump spread, groups of pumps, or add control logic to divide rate between pumps as desired.

    Also, if low flow rates are required, ASC maintains converter lock-up to a lower engine speed than typically seen, and will also achieve and maintain desired flow in converter drive.  If manual control is required for a particular operation, or for a particular pump, the operator can simply exit ASC mode, and control the rig manually.

  • Economy Mode – While in ASC Auto-shift mode, Economy Mode can be selected from the operator control screen, to allow the transmission to select gear and engine speed to provide the most fuel efficient operating point, while maintaining desired flow rate during pumping operation.


The DTOC features available on Cat® well service transmissions add excellent value to any pumping rig in the oil & gas industry, and are available for low, or no cost.  These features simplify operation of the pumping units, making the operation easier, safer, more accurate and more economical.

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