Pumping is a skateboarding technique used to accelerate without the riders' feet leaving the board. Pumping can be done by turning or on a transition, like a ramp or quarter pipe. When applied to longboards, it is also known as Long distance skateboard pumping or LDP. Pumping is a technique similar to pumping a surfboard.
Transition pumping can only be done when there is a slope differential between the front and rear wheels. That is to say, it can only be done at the top and bottom of any ramp, but can be done through the entire pipe. The rider should actually push downward on the truck with the greatest slope under the wheels. On the top of a ramp the front wheels should be pushed, and at the bottom the rear trucks should be pushed. On a pipe the weight should be applied to the rear truck throughout the entire transition.
Flatland pumping is essentially carving with the proper amount of weight application in order to gain momentum. It involves shifting one's weight in sync with the board's movements in order to gain momentum, like pivoting, but with all four wheels on the ground. By keeping the proper timing, the proper foot position, and the proper set up, one can yield great results.
Long Distance Pumping
Long Distance Pumping (LDP), is the name given to Skateboard pumping for any sustained distance (Slalom by contrast is through cones and usually a short distance, maybe 100 cones 6-12ft separation).
LDP riders have been breaking world distance records for 24-hour LDP riding. Recent records include James Peters' 208 mile ride in May 2008 and Barefoot Ted McDonald's 242 mile ride on June 14, 2008 during the Ultraskate IV held in Seattle, Washington which set a new world record.
Learning the technique
Learning to pump is easiest with loose, tight-turning skateboard trucks. Although it is possible to pump with any truck, stiffer more conventional shortboard trucks take much more skill and effort. Trucks with a tight turning radius include Bennett, Tracker, Original, Revenge, and Seismic.
Then front truck is usually mounted on wedged risers to increase the quickness of the turn, and set up with soft bushings. The rear truck on the other hand is de-wedged, to reduce the turn, and set up to be stiff, with harder bushings.