The Hägglunds Spider is the standard control unit for Bosch Rexroth's Hägglunds hydraulic drive systems — PAC, PBC, and DU series. A microcontroller-based controller in an IP65 stainless steel housing, it governs the variable-displacement axial piston pumps that drive Hägglunds hydraulic motors. Its core job is to translate a speed setpoint into precise pump displacement while respecting motor power limits, synchronizing multiple driven shafts, and detecting overload conditions — all with closed-loop feedback.

How does the Spider control pump displacement and motor speed?

The Spider outputs PWM current signals (up to 2 A per channel, 5 A total) to the pump's proportional solenoids — double-coil types like Denison 9A, Brueninghaus EP, and Sauer Sundstrand KA, or single-coil Denison 5A. Speed feedback comes from digital encoders or analog tachometers, closing a PID loop that compares actual speed against setpoint. The PID parameters are configurable through the front-panel text display or a PC serial connection, with password-protected access to prevent unauthorized tuning changes.

How does the electric motor power limitation work?

A current transformer input monitors the electric motor's actual current draw. When motor current approaches the configured limit, the Spider reduces pump displacement — lowering hydraulic power demand rather than tripping the motor overload. This lets the system ride through transient overloads without shutting down, which is critical in applications like shredders and crushers where jam events are routine. Overload detection can also trigger via pressure switch, analog pressure transducer, or speed drop — configurable per application.

What mounting and integration options are available?

The Spider mounts four ways: inside the power unit cabinet, directly in the power unit door, externally on the unit housing, or remotely on a wall using the included brackets or panel flange. For DU-series units, the control panel (LIU) communicates with the Spider via CAN bus, allowing the display to be placed on the cabinet front door while the controller sits deeper in the enclosure. Fieldbus options — Profibus or Modbus — connect the Spider to the plant's overarching control system for remote setpoint commands and status monitoring.