[conjon]

Originally Posted by tsk13

Sankar, thanks for the information. Can you further enlighten us on its working. Earlier I thought it of as a unique way to mount the spare wheel as I had never noticed these being present on both the sides.

this truck has 3 rear axles out of which first one is liftable or retractable(6-7 tonnes rating),the second axle is driven and not liftable,third one is dead axle and not liftable.

As shown in the photo, the 1st rear axle is lifted. say that this truck has a rating of 31 tonnes with all axles active. In this case one is lifted which means the truck is allowed to carry about 24-25 tonnes load.
If the 1st rear axle is made active(put back on the road) the truck can carry another 6-7 tonnes of load.
another advantage is better traction.

This lifting and dropping is done pneumatically(the axle uses air springs).
hope you have understood why it is installed.