Road-rail excavator UNAC 22TRR compact radius

The 22TRR is a high-capacity road-rail excavator that can perform earthwork tasks directly from a railroad track with great freedom of movement and with a large lifting capacity.

Movie of the UNAC 22TRR

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The 22TRR is a self-propelled vehicle with hydrostatic drive.
On the road, this excavator has an excellent turning radius that allows easy manoeuvring and facilitates getting on the rails.
On rails, this excavator moves thanks to a direct hydrostatic drive that does not involve any direct contact with the tyres for precise movements with speeds up to 23 km/h.
This vehicle is initially a Caterpillar excavator on which is maintained the same boom kinematics as the original machine and consequently modified in order to benefit from:

  • An increase and a rearranging of counterweights to satisfy most demanding railway standards and to enable it to lift heavy loads
  • Two UNAC-HDTP motorised rail axles for hydrostatic driving and braking
  • A boom safety system designed to have limited movement when working under live wires.
  • A turret rotation movement that can be blocked in order to secure traffic on an adjacent track
  • A sophisticated system with cameras to see blind spots and to alert the operator of overloads or toppling risks
  • A double cab that can carry a passenger who can also react in case the operator has an ailment.


  • Maintains the original excavator’s lifting and earthwork capacities. The R/R excavator can lift 6 T to a distance of up to 4,50 m from the track centre, in an unfavourable cant situation and can therefore handle heavy equipment or also work off-track
  • Possibility of earthmoving and lifting from a track to the opposite side of the  adjacent track
  • Uses a very secure system which satisfies the most stringent railway standards, authorizing work under live wires or where there is an adjacent track that is open to traffic
  • Electronic security system for the boom’s kinematics (different contact wire height levels) and for the rotation depending on a track’s status (cant and slope, adjacent track side, etc.), as well as a mechanical blocking system
  • Ergonomic controls in a Luxury/Comfort Caterpillar cab that combines comfort, soundproofing, air conditioning, visibility, and ergonomics
  • Possibility of carrying standard excavator attachments, even heavy ones, or railway-specific attachments
  • Very flexible axles that help to reduce risks of toppling and can tolerate high twists of tracks
  • Can work in both directions of a track thanks to the turret’s full rotation and rear-view cameras
  • The Caterpillar initial warranty is officially maintained. The excavator benefits from the UNAC after-sales service and from Caterpillar’s dynamic after-sales network.
  • Approved for travel on the most demanding railway networks.


Technical Data

  • Diesel CATERPILLAR C4.4, ACERT technology
  • Gross horsepower 147 hp / 108 kW at 2 000 rpm.
Road Transmission
  • Electronically-managed hydraulic traction system: 2 speeds
  • 4 driving wheels and 2 steering wheels
  • Speed: from 0 to 30 km/h
  • Speed regulator
  • Axle with a 30T capacity, oscillating front axle: +/-9°, lockable.
Rail Transmission
  • Hydrostatic, 4 wheel drive
  • Central hydraulic motor on each axle: POCLAIN
  • Speed: from 0 to 23 km/h.
Hydraulic Circuit
  • Two serial pumps and two pumps on PTO
  • Specific lifting mode: +7% of lifting capacity
  • Hydraulic tank: 135 L, 220 L circuit.
  • Hydraulic steering for 2 steering wheels
  • Mini turning radius: 6,30 m.
  • Road: the drive axles are equipped with multi-disk brakes with positive action for each wheel. The brakes are activated when the contact is broken, when the brake pedal is pressed, when the handbrake is pulled, when the left armrest is up, or when the emergency stop has been activated.
  • Rail: The hydraulic motors for the rail axles are equipped with positive action disks. The brakes are activated when the contact is broken, when the brake pedal is pressed, when the handbrake is pulled, when the left armrest is up, or when the emergency stop has been activated. A configurable PLC manages the acceleration and deceleration gradient of the rail axle motors.

Luxury/Comfort version, soundproof, ventilated, heated, air conditioned, seat with air suspension that can be adjusted specifically according to the driver’s weight. Steering wheel with adjustable inclination. An electronic dashboard and three digital displays from which the attachments can be controlled, the excavator’s status can be seen in real time, the blind spots (cameras) can be seen, and dangerous movements can be managed.

Fuel Tank Capacity
  • Fuel tank: 235 L
  • Average autonomy: 21 hours, depending on the type of project.
Boom Kinematics
  • Variable Adjustable boom: 5 200 mm
  • Short arm: 2 100 mm
  • Overall weight: 24 000 kg with standard arm
Wheels and Tyres
  • Standard assembly on dual wheels
  • Type of tyres: height 10.00x20 MITAS NB38 wheels with inter-tyre bands