In contrast with the SI-300 model hydraulic lifting machine, the SI-300A model hydraulic lifting machine has a load-bearing structure that can accommodate the installation of a dual tamping system.
When the tamping system is not installed, the SI-300A hydraulic lifting machine has the same functions and performance levels as the SI-300 model, with the exception of the mechanical extension of the supporting vertical columns which is not provided for in this version.
Next to the lifting system, there is a tamping system consisting of a pair of electro-hydraulically controlled mobile tamping heads powered by an additional pump which enables them to tamp any type of track. The tamping heads are able to perform longitudinal movements of 350 mm, in order to position themselves on the sleeper to be tamped, and lateral movements of 620 mm in order to be able to adapt to all types of rail gauge.
Moreover, front rail hook can perform a longitudinal movement of 400 mm which, combined with the longitudinal movement of the tamping heads, enables easy positioning and hooking of the rail at all times.