When Customers Want Change

Caterpillar excavators are known for compact construction and hydraulic systems specifically designed for a narrow application of excavation use. When a customer removes the bucket and adds a hydraulic drill application, then it becomes the designer's problem of making the two distinct applications to work. Not only do you have negative pressure control variable pumps designed for excavation work using cylinders, but several circuits use regenerative flows as well, and a small problem of an original oil tank of only 39 gallons to work with on the excavator.

Two main hydraulic pumps rated at 45-gpm/5000-psi each, and a drill application requiring 80-gpm / 3800-psi. In addition the drill has a high-speed/low-speed mode and cannot be shifted on the fly. A provision to not allow this to happen must be considered as well. And just to make things interesting the customer wants digital pressure readout with outputs to an electronic data controller. Caterpillar did a fine job of compacting this machine into a very small package, and left just enough room for the operator, nothing else. It was clear their intention was to dig holes, not drill holes. This generated a hot three-day debate as to plans to reach this goal.
Drill motor attachment.
Original oil tank removed.

A total redesign of the oil tank to increase capacity from 39 gallons to 93 gallons was done. A circuit design to allow combing the two pumps to provide 79-gpm and controlled by negative pressure control was installed, and operated from existing joystick controls. Installation of pressure transducers and switches to provide digital pressure readout and control of hydraulic two-speed control.

With many ideas, hand drawings and discussion, we found what may have been the only way to provide our customer with all the requirements they wanted, and still keep the Caterpillar looking like a Caterpillar.
View of location of removed oil tank.
Finished look of installation.
New cab controls, LED readout controller, high/low two-speed shift with indicator light.
New oil tank, inspection door open.
Electronic sensors manifold.