The new Blackhawk Classic Series 55-ton capacity trailers have four-position kingpin heights with four deck height/ground clearance settings. These trailers require no shim blocks or trap doors; just move the lever to the setting desired. The "+3/-3" height-control valve allows adjustment at the rear of the deck by turning the spring-loaded leveling valve. The boom well has an extremely low first cross member to reduce the stick height of excavators being transported. Blackhawk Series trailers are designed to deliver the lifting capacity and travel (above and below ground level) to clear obstacles encountered on the road.