TwisterTrac puts vertical autogenous crushing on track

Vertical-shaft impact (VSI) crushers have been the backbone of the Pilot Crushtec product line-up for more than 15 years, with the Tornado crusher having established itself as a leader in vertical autogenous rock-on-rock crushing technology.

Tornado crushers are designed to produce cubical-shaped, high-quality aggregate and sand to meet today’s demanding specifications in contracting, civil engineering and construction projects. Offering enhanced gradation control, these machines are commonly used for the production of fines in industrial and pre-milling applications.

It was the combined understanding of VSI technology and changing customer needs that saw Pilot Crushtec develop the first fully mobile tracked VSI crusher available both locally in South Africa and internationally. Engineered from the ground up and designated the TwisterTrac, the machine comprises a variable-speed belt feeder, a Twister VSI crusher, a discharge conveyor and a diesel-hydraulic power pack, all mounted on a heavy-duty tracked undercarriage with dual-speed configuration and 25º gradability.

Offering rock-on-rock or rock-on-anvil technology, the Twister VSI at the heart of the TwisterTrac is an autogenous crusher that uses a rotor mounted on a vertical shaft to provide the centrifugal force that starts the reduction process. Material fed into the crusher is centralized before entering the modular rotor. The rotor accelerates the material to velocities of up to 90m/s and discharges it into the rock-filled crushing chamber where it collides with other material already in the chamber, providing a continuous crushing action within the crusher.

Engineered for 160 tonnes/h throughput capacity, the TwisterTrac offers variable rotor speeds between 1,200 rev/min and 1,600 rev/min, allowing the crushing ratio to be varied in accordance with application requirements. The 1,000mm diameter crusher rotor has been optimized to ensure an easier flow of materials and all the rotor components are precision machined to eliminate the need for balancing. Replaceable wear parts made from field-tested materials cover all body parts, extending wear life considerably, while rubber mountings on the bearing housing eliminate vibration transfer to the rest of the plant.

The TwisterTrac is equipped with a heavy-duty 6m3 hopper and a load-sensing belt feeder with an 800mm wide belt. The discharge conveyor has a 3.7m discharge height and features a tail section that can be hydraulically lowered for easier access.

The machine is powered by a Cat C12 diesel engine, with a rated output of 317kW at 2,100 rev/min, driving Sauer-Danfoss load-sensing hydraulics. This power pack incorporates an engine-protection system with monitoring integrated into the main PLC that controls the entire machine.

The PLC automates all the crusher’s features and facilitates continual monitoring of all aspects of the machine’s operation. It also provides a number of safety and diagnostic features, and has an integrated warning and automatic shutdown facility.

With its modular configuration, the TwisterTrac has been designed to minimize maintenance; examples of this include a rock box with replaceable build-up plates and a taper-shaft rotor mount for quick and easy removal. A convenient inspection hatch allows visual access for rotor inspection, while a hydraulically controlled swing-open mechanism allows access to the crusher and rotor in minutes without the need for lifting equipment.

The prototype of the TwisterTrac was tested in harsh local operating conditions to verify its performance criteria. Two crushers have since been put to work in Ireland crushing aggregates for roads, while another is operating successfully in a hard rock application in Bulgaria producing aggregate for a EU-funded road project. Units in Australia are being used in a mining application and a quarrying application producing sand, while locally a TwisterTrac is producing aggregate in a high-silica-content hard rock quarry.

Pilot Crushtec (Pty) Ltd, PO Box 30032, Jet Park 1469, South Africa; tel: +27 11 842 5600; fax: +27 11 842 5610.