Triple-stage Mast

A three-stage mast also known as a triplex mast, is a telescoping mast comprised of an outer stationary frame, and two inner moveable frames. When lifting the fork carriage it first raises the full extent of the stationary outer mast channel known as the "free lift" dimension. After which both inner frames begin to extend - the inner most leading the way. The construction allows the minimum collapsed or lowered height with the maximum obtainable fork elevation. The advantages are found when extended heights must be able to reach tall racks while the vehicle must negotiate or travel under lower door openings or obstructions.