The extendable frames manufactured by TRACKONE may be divided into the following categories: "parallel extension", "telescopic extension" and "mechanical track variation".

  1. PARALLEL EXTENSION. In this type of frame translation of the side members occurs by means of staggered sliding cylindrical pairs distinct on each side. The extensions are welded to the chassis and hence have distinct non-coinciding axes. Two hydraulic cylinders drive the track expansion and contraction movement. Because of the nature of the sliding seats, this type of frame has reduced play and is suitable for small cranes and small drilling machines.

  2. TELESCOPIC EXTENSION. In this type of frames, translation of the side frames occurs by means of an innovative system of concentric cylindrical pairs where the extensions (male) are welded to the side frames, while the sliding seats (female) and the central reaction guide are welded to the central body. The left and right sliding pairs share the same axis and, unlike the other undercarriages of the same category, have the same dimensions, thus guaranteeing perfect frame symmetry. Two opposed hydraulic cylinders drive the track expansion and contraction movement. This type of undercarriage is widely used in cranes, anchor drilling rigs and rotary drilling rigs

  3. MECHANICAL TRACK VARIATION. In this type of frame, the side frames are bolted onto the central body. The position of the bolts allow varying the frame track by a predefined pitch. There are no hydraulic cylinders. This system allows only small total track variations, but has the advantage that there is no wear of any kind and very high robustness is ensured. It is mainly used in excavators and forestry machines.


Other types of extendable undercarriage can be developed on the customer's request.

Moreover, these undercarriages are supplied complete with base bearing (slewing ring) rotating distributor joint and hydraulic pipes ready for assembly on the customer's machine.
Some examples are listed here below.

  • Extendible Undercarriage with parallel pistons

    trackone prodotti sottocarro estendibile a sfili paralleli

    Extendable crawled frames, with parellel extension, B0 class with machine-basis and hydraulic stabilizers. Conceived to be used on small drilling machines and suitable for machines having a total weight up to 8 tons. Total track closed 520 mm., total track open 980 mm. Max speed 1,4 km/h, max output torque 9 kNm.

  • Extendible Undercarriage with telescope pistons

    trackone prodotti sottocarro estendibile a sfili telescopici

    Extendable crawled frames, with telescopic extension, B5 class. Conceived to be used on anchor drilling rigs and rotary drilling rigs. Suitable for machines having a total weight up to 40 tons. Total track closed 1.900 mm., total track open 3.100 mm. Max speed 5 km/h, max output torque 45 kNm.

  • Extendible Undercarriages with mecchanical variation of the gauge

    trackone prodotti sottocarro estendibile con variazione meccanica della carreggiata

    Extendable crawled frames, with mechanical track variation, B5 class with base bearings and rotating distributor joint. Conceived to be used on excavators and forestry machines. Suitable for machines having a total weight up to 21 tons. Total track closed 2.050 mm., total track open 2.385 mm.
    Max speed 5 km/h, max output torque 45 kNm.