Overview - 40-Taper Gearbox

Applies to machines built from: 
January, 1989


  1. Low-gear air tube [1]
  2. High-gear air/oil tube [2]
  3. High-gear proximity sensor [3]. This sensor is normally open (initially de-energized).
  4. Low-gear proximity sensor [4]. This sensor is normally closed (initially energized).
  5. Gear-shift piston [5]
  6. Inputs column on diagnostic screen [6].

This video shows how the gearbox changes gears:

  1. The control sends air to the low [1] or high-gear tubes [2].
  2. The low-gear [1] air tube sends air to the gear-shift piston [5], or the high-gear [2] air/oil tube sends oil to the gear-shift piston [5].
  3. The gear-shift piston moves into the correct position.
  4. The proximity sensors [3 and 4] read the position of the gear-shift piston [5].
  5. The DIAGNOSTIC page on the display [6] shows if you are in low or high gear.

The low gear and high-gear proximity sensors behave differently:

  • The high-gear proximity sensor [3] is normally open. In high gear, the piston shaft does not engage the proximity sensor.
  • The low-gear proximity sensor [4] is normally closed. The piston moves down to engage the high-gear [3] proximity sensor, and then the low-gear [4] proximity sensor.

Be aware: Many service and repair procedures should be done only by authorized personnel. The service technicians at your Haas Factory Outlet (HFO) have the training, experience, and are certified to do these tasks safely and correctly. You should not do machine repair or service procedures unless you are qualified and knowledgeable about the processes.

Danger: Some service procedures can be dangerous or life-threatening. DO NOT attempt a procedure that you do not completely understand. Contact your Haas Factory Outlet (HFO) and schedule a service technician visit if you have any doubts about doing a procedure.