EHS: Efficient High Speed Drive

EHS is similar to the field-proven and revolutionary hydrostatic drive system that Tigercat initially developed and released in 1996 with the first 630 series skidders.

Like Tigercat’s standard hydrostatic drive system, EHS consists of two variable displacement motors as inputs to the Tigercat transfer case. Front and rear output shafts are connected directly to the front and rear axles.

While the standard electronically controlled hydrostatic drive system performs exceptionally well, EHS is capable of providing the tractive effort of the deepest gear ratio offered in Tigercat’s standard transfer case as well as the top speed of the shallowest gear ratio offered in the standard transfer case.

This is accomplished with more sophisticated computer logic and the ability to take one of the drive motors offline when high tractive effort is not required. In this case all pump flow is directed to one hydraulic motor, increasing both travel speed and motor efficiency.

When operating conditions demand high tractive effort, both hydrostatic motors are working. When tractive effort requirements are reduced — for instance, when traveling empty or loaded on flat terrain — all of the pump flow is directed to one motor for higher travel speeds.

Tigercat is offering EHS as standard in the 610C and 615C. EHS is optional for the 620D and 620E skidders.

BTB 37: EHS and the new E-series skidders

Published on: Tuesday 1st July 2014

Early in 2014, Tigercat released the E-series skidders. Available in North America and Europe, the 620E, 630E and 635E skidders are powered by the Tigercat FPT N67 Tier 4i engine. The 620E is rated at 164 kW (220 hp) and the two larger models at 190 kW (260 hp).