08 - Wheels / Axles. Wheels / Axles. January GGF Page 8-1

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1 Wheels / Axles January GGF Page 8-1

2 This Page Intentionally Left Blank Page GGF January 2005

3 Contents Chapter Preface Parts List Tools List Supplies List Glass List Process Overview Wheels and Axles Brake Lines and Cuffs Install Main Gear Axles Nose Wheel Installation January GGF Page 8-3

4 8.0 - Chapter Preface Parts List Part Number Description Qty Nylaflow Brake Lines 10' Gear Cuff, Pilot 1 Gear Cuff, Co-Pilot 1 Aluminum backing plate 2 Main Gear Axles 2 AN5-34A Bolt 4 AN6-34A Bolt 4 AN Washer 4 AN Washer 4 MS Locknut 4 AN Locknut 4 Wheel Assembly 2 Rim 2 Tube 2 Tire 2 Wheel Assembly 1 Fork 1 Rim 1 Tire 1 Tube 1 Set Screw 1 Axle 1 Screw 1 Phenolic Washer 1 Large Washer 2 Belleville Washer 4 Nylock Nut Tools List Description Long Level Roll Tape Measure Plumb Bob Aluminum Ibeams Supplies List Description Bondo EZ-Poxy DOT 5 Brake fluid Page GGF January 2005

5 Glass List Type Size Qty BID 2" x 36" 2 BID 4" x 18" 4 TRIAX 4" x 3"-6" Process Overview Construction Process Main Gear Jig Fuselage Route Brake Lines Attach Gear Cuffs Build TRIAX Axle Pads Fabricate Aluminum Baking Plates Mount Axles Completion Date Nose Gear Assemble Nose Wheel Adjust Nose Wheel January GGF Page 8-5

6 8.1 - Wheels and Axles Brake Lines and Cuffs Suspend the fuselage by blocking it up under the outboard ends of the center section spar and also under the belly just aft of the nose gear. Get it level forward-aft, rightleft with the main gear tips about 7" off the ground. If the gear is uneven, trim the longest one down. You can check the gear leg length by using a line level suspended from a piece of string. Attach the string to the bottom of one of the gear legs and stretch it to the bottom of the other. Do not reference gear leg length by the floor. You may have a slanting floor. 2 ply BID Straw Brake line Gear leg Forward Bondo Figure 8-1. Brake line attachment to main gear leg. The brake lines must be installed before the axles and gear leg cuffs. Route the appropriate brake lines down the rear of each gear leg. Slide drinking straws down over the brake line. Sand the back edge of the gear leg and Bondo the straws into place using the brake lines to hold the routing.. Sand smooth once the Bondo has cured, but take care not to abrade the straws too much. The straws will allow you to replace the brake line in the future if needed. Apply a 2" wide strip of BID tape, glassing the line to the gear down to within 8" of the gear end. Allow about 15" of free tubing to extend past the point where the tape glass ends. Be sure that there is at least 1/2" - 5/8" clearance between line and where the tubing comes through the fuselage side. Radical movement of the gear during extremely hard landings could sever the brake line if adequate clearance is not provided. Slide the gear cuffs up the legs to mate with the fuselage sides. Sand the edges of the cuffs smooth so that they conform to the fuselage sides. When you are happy with the fit, Bondo or hot glue them into place. With the gear unloaded, the cuffs should be approximately 1/16" away from the fuselage sides at the bottom and 3/16" away at the top. Permanently bond them to the gear leg with 2 plies of BID around the bottom of the cuff extending onto the gear leg. Any interference between the cuff and fuselage when gear is loaded can be sanded away later Install Main Gear Axles Sand the lower 6" on both gear legs thoroughly. Measure 2 up from the bottom of shorter landing gear and place a mark. Now go to the outside of the gear leg and find the center line of the gear leg. Draw a line down the center. Draw another line parallel to this first line but 1/4 aft of the first. Where the aft vertical line meets your 2 from the bottom mark is your axle center position. Center your axle over this location and clamp it in place. The smaller holes go on top. When satisfied with your position drill the 4 axle holes using your axle as a template. Temporarily install your axle using (2)AN5-32A bolts and (2) An6-32A bolts. Using your line level and string place one side on the 2 inch mark you made on the gear leg. Stretch the string to the other gear leg and mark you axle center point on that gear leg as well. Page GGF January 2005

7 Transfering 2 axle mark to other gear leg Bottom of Gear Leg Center point of axle 2 1/4 Figure 8-2 Axle Location With the airplane level you want to have 10 deg. Kick down at the axle. Gear leg (front view) Out Down Figure 8-3. Main gear axle pad. Use washers to space axles I prefer to wait until the airplane has the engine and wings on it before I do the next steps. If it is done before however, it may just require some shims to get the proper axle position. Jack the airplane off the ground and level it from left to right. Using 3/8 washers on the bottom bolts shim the back of the axle until you have 10 degrees down at the ends of the axle. This will get the camber needed for a fixed gear. Refer to Figure 8-3. January GGF Page 8-7

8 Now you can put the airplane back on the ground. Before we make a permanent pad we will check the toe-in. Roll the airplane back and forth 5-6 feet a few times. Drop a plumb bob off the nose of the airplane and make a mark on the floor. Stretch a string between your two axles and measure it. Find your center point and draw a mark on the floor. Connect your marks on the floor. This is your center line. Take the two long I-beams and line then up on the sides of your tires. Measure the distance from the center line to the I-beam right behind one of your tires. Measure the distance from your nose mark straight out to the I-beam. The proper toe-in will have a 1 less measurement at the nose. If your airplane is different you will need to shim the axles. Expect to get approximately 1 change per.010 shim. A standard washer is about.060. Make sure the beams are fla t against the tires Aircraft C Aluminum I-beams Th is d im e n sio n w ill b e o n e inch less than the m easurement ta ke n a t the tire s Figure 8-4. Checking Toe-In Once the axle position is established you can make a permanent pad that will hold the proper axle location. Remove the axle and cover the base with one layer of duct tape. Cover your AN5 and AN6 bolts with DC-4 or Vaseline. Reinstall the axle to the gear leg being careful not to get the washers covered with the vaseline. If they get some on them after assembly wipe them off with a little alcohol on a rag. Mix up a batch of Flox and EZpoxy. Put a little Cabosil in it to make it a little sticky. Pack this mixture between the axle and the gear leg. Be sure it gets in all around the washers. Conform it so that it follows the curve of the axle base. Let this cure. After the mixture is cured come back and remove the axle and bolts. The washer will be captured in the mix and will not come out. Remove the duct tape from the axles. Page GGF January 2005

9 Before you reinstall the axles a backing plate will need to be made to fit between the back of the gear leg and the nuts. You will also attach your wheel pant bracket to this plate. Install the plate as shown in Figure /2 1/2 Figure 8.5 Backing Plate Spacing The last step is to relieve the bottom of the gear leg for the brakes. You may have to grind a little on the gear leg to get clearance for the caliper to move freely. Allow at least 1/8" clearance. Make sure you do not grind too much material around the lower rear bolt hole. Move the caliper through its travel in and out and make sure you have clearance. Now install the brake lines to the assembly. Use 1/8" pipe, 3/16" tubing, a 90 degree fitting, and liquid Teflon seal. Once the system is all hooked up, add DOT5 brake fluid and bleed the system from the bleeder on top of the brake assembly. The top of your brake master cylinders reads dot3. Dot 3 is not compatible with the Matco brakes so it is a good idea at this time to mark the tops of your master cylinder DOT5 to avoid confusion in the future. January GGF Page 8-9

10 CL Outboard Rear Axle MS or AN locknuts Torque plate Axle flange Slave cylinder Gear leg Backing plate AN5-34A bolt (top) AN6-34A bolt (bottom AN or -616 washers ) Install bolts from this side Figure 8-5. Main gear axle assembly detail. Bleeder fitting Brake Caliper Figure 8-6. Brake assembly side detail. Page GGF January 2005

11 8.2 - Nose Wheel Installation The fork assembly comes with the axle, shims, and set screw in place. Assemble the nose wheel, tire, and tube with the three 5/16" X 3" bolts and locknuts provided. Inflate tire to 45 psi, and maintain it at that pressure. Grease the axle and spacers. with a little wheel bearing grease. Lock axle into place using the set screws provided. Install the fork and wheel onto the nose gear using the diagram below. Tighten the nylock nut until it takes about pounds to rotate the tire when pushing on the rear of the tire. This is a good starting point. Experiment until you have it loose enough for easy taxiing while being tight enough to prevent shimmy. It is better to be tighter. Spacers Set screw Set screw notch Phenolic washer Strut flange Large washer Fork Belleville washers (3) Set Screw Nylock nut Figure 8-7. Nose wheel assembly. Note: It is extremely important throughout the operation of the Velocity to maintain proper inflation in the nose wheel tire and adequate pressure on the Belleville washers. The Belleville washers prevent shimmying, which can be disastrous in a tricycle-gear aircraft such as the Velocity pounds pressure rotate laterally Figure 8-8. Nose wheel. January GGF Page 8-11