trench & pit excavation

-diesel power unit on crawler tracks (backactors)
face shovels -hydraulic rams

backactors scope the soil forward
-these machinese are available as cable rigged or hydraulic excavators
-suitable for trench and bulk excavating
-cable rigged backactors are usually available with larger bucket sizes and deeper digging capactities than the hydraulic machines
-but hydraulic machines have a more positive control and digging operation and are also easier to operate.

Face shovels
-These machines are designed to excavate above their own wheel or track evel and are suitable for bulk excavation work
-In basement work , they will require a ramp approach unless they are to be lifted out of the excavation area by means of a crane
-Face shovels are available as cable rigged or hydraulic machines