1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there
2、from, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2017 SAE International All rights reserved. No part of this p
3、ublication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-497
4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/standards.sae.org/AIR5388 AEROSPACE INFORMATION REPORT AIR5388 Issued 2001-06 Reaffirmed 2017-05 Unique Wheel and
5、 Brake Designs RATIONALE AIR5388 has been reaffirmed to comply with the SAE Five-Year Review policy. INTRODUCTIONWheels and brakes in current use are generally very similar in design configuration. This has resulted from the sum of experience gained through the years as various designs were tried to
6、 meet unique requirements. Typical of modern brakes are the steel and carbon heatsink brakes shown in Figures 1 and 2. They consist of a forged aluminum piston housing, forged steel torque tube and a heat sink consisting of a pressure plate, alternating rotors and stators and a backing plate. Mechan
7、ical adjusters are used, generally of an extruding tube design. On carbon-carbon composite heat sink brakes, the adjusters are integral with the piston assemblies. On steel brakes, they are generally separate units. For bogie gears, the brake is bearing mounted on the axle, with one bearing being in
8、tegral with the piston housing and the second at the mid-length of the torque tube. On two-wheel twin gears, the brake may be either bearing mounted or flange mounted.Figure 3 shows a typical wheel design. Wheels are typically forged aluminum with an “A” cross-section. To accommodate the large brake
9、s required, the web is normally offset significantly to the outboard side. Fuse plugs and over pressurization protection devices are included.This Aerospace Information Report describes wheel and brake designs that are not typical, resulting from unique requirements and in some cases working very su
10、ccessfully.FIGURE 1 - Typical Steel Heat Sink Brake_SAE INTERNATIONAL AIR5388 2 of 40FIGURE 2 - Typical Carbon Heat Sink Brake_SAE INTERNATIONAL AIR5388 3 of 40FIGURE 3 - Typical Current Wheel Design_SAE INTERNATIONAL AIR5388 4 of 40TABLE OF CONTENTS1. SCOPE .71.1 Purpose.72. REFERENCES .73. UNIQUE
11、WHEEL AND BRAKE DESIGNS .73.1 Liquid Cooled Brake73.2 XB-70 103.3 F-4.153.4 B-58 173.5 Beryllium Heat Sink Brakes 213.5.1 C-5A 213.5.2 Space Shuttle243.5.3 Buran 283.6 747 Encapsulated Carbon Brake 293.7 ABSC Turbo Brake .313.8 SR-71 333.8.1 Background .333.8.2 Wheel Features.363.8.3 Brake Structure
12、 .363.8.4 Brake Heat Sink 363.8.5 Landing Gear Uplock 373.8.6 Program Security 373.9 Electrically Actuated Brakes .373.9.1 ABSC A-10 Brake .373.9.2 BF Goodrich F-16 Brake .404. KEYWORDS .405. ACKNOWLEDGMENT 40_SAE INTERNATIONAL AIR5388 5 of 40TABLE OF CONTENTS (Continued)FIGURE 1 Typical Steel Heat
13、Sink Brake 2FIGURE 2 Typical Carbon Heat Sink Brake 3FIGURE 3 Typical Current Wheel Design4FIGURE 4 Liquid Cooled Brake Schematic .8FIGURE 5 Liquid Cooled Brake Cross-Section .9FIGURE 6 Liquid Cooled Brake Installation on 727 .11FIGURE 7 XB-70 Gear Retraction Sequence12FIGURE 8 XB-70 Brake Installat
14、ion.13FIGURE 9 XB-70 Brake Actuators .14FIGURE 10 F-4C Wheel and Brake Design.15FIGURE 11 Cross-Section of the F-4C Brake With Bearing Can 16FIGURE 12 F-4D Brake Cross-Section With Strengthened Wheel .17FIGURE 13 B-58 Landing Gear Retraction Sequence 18FIGURE 14 B-58 Original Wheel Design .18FIGURE
15、15 B-58 Non-Frangible Wheel.20FIGURE 16 Original C-5A Beryllium Rotor and Stator.22FIGURE 17 Final C-5A Brake Disk Design 23FIGURE 18 Space Shuttle Brake.24FIGURE 19 Space Shuttle Stator Design 25FIGURE 20 Space Shuttle Rotor Design .26FIGURE 21 Space Shuttle Wheel Design27FIGURE 22 Beryllium Rotors
16、 for the Russian Buran Space Shuttle28FIGURE 23 747 Encapsulated Carbon Rotor Segment Parts .29FIGURE 24 747 Encapsulated Carbon Rotor Assembly .30FIGURE 25 ABSC Turbo Brake With Auxilliary Disk Brake.32FIGURE 26 ABSC Turbo Brake With Auxilliary Expander Tube Brake .33FIGURE 27 SR-71 Wheel, Brake, T
17、ire, and Strut Assemblies 34FIGURE 28 Cross-Sectional View of theh SR-71 Brake and Axle.35FIGURE 29 Cross-Section of the A-10 Electrically Actuated Brake 38FIGURE 30 Control System for the A-10 Electrically Actuated Brake .39_SAE INTERNATIONAL AIR5388 6 of 401. SCOPE:This SAE Aerospace Information R
18、eport (AIR) has been prepared by a panel of the SAE A-5A Committee and is presented to document unique design approaches used for aircraft wheels and brakes.1.1 Purpose:The purpose of this AIR is to describe wheel and brake designs possessing unique features or approaches to allow them the meet the
19、requirements of the particular airplane for which they were intended. Wherever possible, the requirements driving these design and the lessons learned are documented. This AIR is intended to document the ingenuous solutions that have lead eventually to the wheel and brake designs in use today and po
20、inting to the brakes for tomorrow.2. REFERENCES:There are no referenced publications specified herein.3. UNIQUE WHEEL AND BRAKE DESIGNS:3.1 Liquid Cooled Brake:In the early 1950s, BF Goodrich became interested in alternate braking methods because of the introduction of the commercial jet aircraft. T
21、he older propeller-type aircraft could generate large retarding forces by reversing the pitch of the propellers. RTO energies were in the range of 10 to 20 million ft lb, and the wheels had a 20 to 22-inch bead seat diameter. With the introduction of jet powered aircraft, the energy requirements inc
22、reased to the 20 to 50 mft-lb while the bead seat diameter was reduced to 16 to 18 inch range.One alternative method that BF Goodrich decided to proceed with was a liquid cooled brake. In its final form the brake consisted of a two-rotor brake, a closed loop primary heat exchanger, and a secondary h
23、eat exchanger system using plain water. The primary system used a special glycol/water fluid, to prevent freezing, with inhibitors and anti-foaming agents added. A pump driven by a ring gear attached to the wheel was used to circulate the fluid used in the primary system. The fluid was pumped throug
24、h the brake to a liquid-to-liquid heat exchanger where the energy was transferred from the primary fluid to the secondary fluid. The secondary fluid was plain water (distilled or de-ionized water to reduce scale buildup). An expansion tank was provided to allow expansion of the heated primary fluid,
25、 and to provide a way to pressurize the primary fluid to reduce cavitation at the pump inlet during spin up. During development the expansion tank/pressurization system was changed to a bladder type accumulator.Figure 4 shows the general schematic of the system. _SAE INTERNATIONAL AIR5388 7 of 40FIG
26、URE 4 - Liquid Cooled Brake Schematic3.1 (Continued):Figure 5 shows a cross-section of the brake. The primary fluid enters the brake to a plenum chamber. One-fourth of the fluid is routed to the fluid passage in each annular piston and one-half is routed to the center section (stator). The two rotor
27、s rub against four copper surfaces. Heat is generated as energy is absorbed, and is transferred to the primary fluid behind the copper face. The fluid flow turns 180 to another plenum chamber in the brake and then exits to the heat exchanger._SAE INTERNATIONAL AIR5388 8 of 40FIGURE 5 - Liquid Cooled
28、 Brake Cross-Section3.1 (Continued):The actuation fluid is the same glycol/water compound as the primary fluid. This allows the use of the same compound for all the seals in the brake. The two large annular pistons are activated by a master cylinder type transfer valve which converts the 3000 psi ai
29、rcraft skydrol system to the lower pressure glycol/water system. The emergency air system also acts though the same master cylinder at the shuttle valve.The LCB was first tested on a clipped wing B-26 for ground testing. An installation on the Boeing 367-80 (Dash 80) was made at in 1957 and an updat
30、ed installation was made in 1959 and a third installation was made on a United 720 in 1961. _SAE INTERNATIONAL AIR5388 9 of 403.1 (Continued):The first 727 installation was made in 1963 on United E29. During the test work for this installation, a unit was developed which pulled a negative pressure o
31、n the system then filled the primary system with fluid under pressure. This unit was successful in reducing the entrained air in the fluid, and greatly reduced the cavitation problem. The unit was also used to fill the actuation system and eliminated the need for a tedious bleeding procedure. The al
32、uminum heat exchanger, which worked so well in the lab, developed weld cracks when exposed to the cantilevered environment of the aircraft strut and was replaced with a stainless steel design. It was also found that the torque level had to be increased to compete with the seven rotor steel brake.Thi
33、s work resulted in the installation and certification on a United 727, 049U, in 1963. The 727 installation in shown in Figure 6.The other significant feature, when using the LCB, was the notable improvement in tire life. The improved tire life was probably due to several factors:1. The spin-up load
34、of the LCB is only about 5% of that of the steel brake mass.2. The smoothness of braking generated far less skid control activity at the high speed end of the stop which reduced tire scrubbing.3. The lower wheel and brake temperatures; especially, during certification testing, saved a lot of tires.T
35、he weight of the LCB system was approximately 5% greater than the seven-rotor steel brake. It was considered possible to offset this if the LCB could have been considered in the preliminary design stage of the aircraft instead of retrofitting an existing strut design.While not a commercial success,
36、the LCB was a technical success in that a research lab curiosity was certified for use on the 727. The fact that a system was developed which pumped heat out of the wheel, brake, tire package, and dissipated it by a phase change liquid may yet have some future application.3.2 XB-70:The XB-70, like m
37、ost supersonic aircraft, lack room for storage of the landing gear. This resulted in tire and wheel sizes that did not provide sufficient room for the required brakes. Figure 7 shows the XB-70 gear retraction sequence. The solution in this case was the use of one large brake for the two wheels on ea
38、ch axle. An internal shaft connected the two wheels. Brake rotors were keyed to this shaft._SAE INTERNATIONAL AIR5388 10 of 40FIGURE 6 - Liquid Cooled Brake Installation on 727_SAE INTERNATIONAL AIR5388 11 of 40FIGURE 7 - XB-70 Gear Retraction Sequence3.2 (Continued):The general configuration of the
39、 landing gear was a four-wheel bogie with two wheels in-line forward and two wheels in-line aft. The wheel bearings rode on a large diameter axle. Inside the axle, an internal shaft was used to mechanically connect the inboard and outboard wheels. The middle of the shaft (lengthwise) was keyed to dr
40、ive the brake rotors. The stators were keyed on their outer diameter and engaged a frame. The frame was, in essence, a torque tube bolted the bogie (see Figure 8). If the internal shaft is removed, the heatsink could be removed by unbolting the frame from the bogie, without jacking or wheel removal.
41、_SAE INTERNATIONAL AIR5388 12 of 40FIGURE 8 - XB-70 Brake Installation3.2 (Continued):Brake actuators. Figure 9, were mounted to a steel manifold that was bolted to the bogie, independently from the torque frame. Brake actuators were mounted at both ends of the heatsink.The pistons were powered in b
42、oth the brakes-on (extension) and brakes-off (retraction) directions with a detent to hold the piston in the retracted position. The detent was later replaced by a retractor spring and plate._SAE INTERNATIONAL AIR5388 13 of 40FIGURE 9 - XB-70 Brake Actuators3.2 (Continued):Lessons Learned:1. The co-
43、rotating main wheels caused problems on short radius turns2. Because of the key friction and the large number of disk pairs, little normal force was generated between the center disks.3. Heatsink installation was difficult.4. Hydraulic retraction of pistons complicates the design.5. Piston detents c
44、an cause problems_SAE INTERNATIONAL AIR5388 14 of 403.3 F-4:On the F-4, like many of the fighter aircraft, the space (width) available for the brake was very limited.The designer, therefore, made as much use of the space within the tire width for the brake as possible. This resulted in the use of la
45、rge diameter wheel bearings with the inner races riding on the outer diameter of the brake piston housing.One of the design considerations was to allow the wheel and tire to be removed without removing the brake. The configuration for the F-4C, which allowed this, is shown in Figure 10. The F-4C design featured a bearing can fitted over the brake. The bearing can was keyed to
