Strut piston Lower locating cam Strut cylinder Upper locating cam Figure 13-44.  cutaway view of a nose gear internal centering cam.  Landing Gear Rigging and Adjustment pressure or surface wear, corrosion or pitting, discoloration  from excessive heat, cracked or broken bearing cages, and  scored or loose bearing cups or cones that would affect proper  seating on the axle or wheel. If any discrepancies are found,  replace the bearing with a serviceable unit. Bearings should  be lubricated immediately after cleaning and inspection to  prevent corrosion.  To lubricate a tapered roller bearing, use a bearing lubrication  tool or place a small amount of the approved grease on the  palm of the hand. Grasp the bearing with the other hands  and press the larger diameter side of the bearing into the  grease to force it completely through the space between  the bearing rollers and the cone. Gradually turn the bearing  so that all of the rollers have been completely packed with  grease.  [Figure 13-45]  Occasionally, it becomes necessary to adjust the landing  gear switches, doors, linkages, latches, and locks to ensure  proper operation of the landing gear system and doors.  When landing gear actuating cylinders are replaced and  when length adjustments are made, over-travel must be  checked. Over-travel is the action of the cylinder piston  beyond the movement necessary for landing gear extension  and retraction. The additional action operates the landing  gear latch mechanisms. grease gun. Follow manufacturer’s instructions. Before  applying grease to a pressure grease fitting, be sure the fitting  is wiped clean of dirt and  debris, as well as old hardened  grease. Dust and sand mixed wit h grease produ ce a very  destructive abrasive compound.  Wipe off all  excess grease  while greasing the gear. The piston rods of all  exposed strut  cylinders and actuating cylinders s hould be clean at all times. Periodically, wheel bearings must be removed, cleaned,  inspected, and lubricated. When cleaning a wheel bearing, use  the recommended cleaning solvent. Do not use gasoline or jet  fuel. Dry the bearing by directin a blast of dry air between  the rollers. Do not direct the air so that it spins the  bearing as  without lubrication, this could cause the bearing  to fly apart  resulting in injury. When  inspecting the bearing, check for  defects that would render it  unserviceable, such as cracks,  flaking, broken bearing surfaces, roughness due to impact  A wide variety of aircraft types and landing gear system designs  result in procedures for rigging and adjustment that vary from  aircraft to aircraft. Uplock and downlock clearances, linkage  adjustments, limit switch adjustments, and other adjustments  must be confirmed by the technician in the manufacturer’s  maintenance data before taking action. The following examples  of various adjustments are given to convey concepts, rather  than actual procedures for any particular aircraft. Figure 13-45.  Packing grease into a clean, dry bearing can be done by hand in the absence of a bearing grease tool. Press the bearing  into the grease on the palm of the hand until it passes completely through the gap between the rollers and the inner race all the way  around the bearing. 13-26