Drill Jumbos used in tunnels are also known as Tunnel jumbos.
A drill jumbo is portable carriage having one or more carriage having
one or more working platform equipped with columns, bars or booms to
support and guide the drills, enabling the drills to perform drilling
operation at desired pattern.
These platforms have arrangement for supporting the compressed air
pipes, water pipes.
The booms are operated by hydraulic fluid or air and supports the
drifters.
The platforms are constructed as per the size of tunnel and can be
raised or lowered.
Several drills can be operated from each platform for speedy
excavation.
The jumbos have 1,2 or 3 booms and have high rate of penetration, say
2 to 3 meter per minute.
The jumbos are mounted either on rails or on pneumatic tyres
depending upon the type of work.
The jumbo can be equipped with electricity feeding cables, pneumatic
concrete placers etc.
Mobile jumbos of modern design with four-wheel drive and centrally
articulated steering speeds production and reduces tunnelling costs.