CA1094403A

CA1094403A - Method of coating interior of hollow axle

Info

Publication number: CA1094403A
Application number: CA271,449A
Authority: CA
Inventors: Frank H. Fisher
Original assignee: Rockwell International Corp
Current assignee: Boeing North American Inc
Priority date: 1976-02-17
Filing date: 1977-02-09
Publication date: 1981-01-27
Also published as: NL7701305A; GB1546977A; DE2706801C2; FR2341375A1; MX4418E; SE7701699L; FR2341375B1; DE2706801A1

Abstract

METHOD OF COATING INTERIOR OF HOLLOW AXLE

Abstract of the Disclosure A method of coating the interior surface of an axle assembly in which the axle is a hollow axle and the interior of the axle provides a storage area for pressurized fluid comprising the steps of blowing air through the interior of the axle to clear the interior of metal chips and the like, washing the interior with a flow of steam to remove any remaining foreign material including oil, drying the interior, spraying the interior with a sprayable, non-peelable plastic coating, drying the coating.

Description

9'1~03 METHOD OF COATING INTERIOR OF HOLLOW AXLE

Background of the Invention This invention is directed to an axle assembly for a vehicle and, more specifically, to a trailer axle assembly including fluid powered brake mechanisms and a brake fluid relay valve mounted directly to the axle as a unitary assembly. The invention is particularly applicable to a trailer axle utilizing an anti-skid brake control system and provides a mounting plate for securing the brake control or relay valve directly to the axle.
Anti-skid brake control systems are now required on many commercial vehicles in the United States and are being adopted in other countries in the inter~st of traffic safety. One such system is disclosed in United States Patent No. 3,790,227 which issued to L. C. Dozier on February 5~ 1974. A brake control valve which may be employed in such a system is disclosed in United States Patent ~o. 3,740,105 which issued to A. B. Holmes on June 19, 1973.
Relay valves are used on trucks and trailers to supply air from a source such as an air reservoir to the vehicle brakes when the vehicle operator depresses the brake pedal. The relay or control valve in an anti-skid brake system operates in direct response to depression of the brake pedal, but also includes means for modulating the vehicle operator directed application of the brake fluid pressure in the event a wheel or wheel set decelerates at such a rate as to indicate an incipient skid condition. In such a system the angular velocity of the wheels at opposite ends of an axle is monitored by sensors which emit electrical signals indicative of the angular velocity of each wheel or wheel set and the signals are compared by electrical means. If an incipient skid condition is detected, the electrical means actuates an override device to modulate the vehicle operator directed application of brake fluid pressure until such time that the incipient skid condition no longer ~0~ ~03 exists or the vehicle is brought to a stop. In the control valve disclosed in the aforesaid patent, the override device is a solenoid which operates a valve to modulate the application of control pressure to the relay valve.
Ihe solenoid is actuated by an electronic computer which is mounted in the relay or control valve body and electrically connected to the wheel speed sensors and the solenoid.
Relay or control va]ves are usually mounted directly to the chassis or frame of a truck or trailer where they are protected from road shock and axle vibration by the vehicle suspension. With the advent of safety regula-tions requiring anti-skid brake control systems for each axle of a vehicle, it has become apparent that certain advantages could be obtained from the use of a self-contained anti-wheel lock axle assembly requiring only an electrical connection to a power source and fluid pressure connections, usually air lines, to a source of fluid pressure and to the operator actuated brake pedal.
l~e above-noted fluid pressure has been typically stored in the prior art in storage bottles and the like. ~ore recently, trailer axle assemblies have utilized hollow axles as a storage reservoir for fluid pressure used to actuate the trailer brakes. The interior surface of such hollow axles must be suitably clean and treated so that the quality and cleanliness of the operating air can be maintained at a high level. The maintenance of the quality of the fluid pressure (air) is important for a number of reasons, including the reduction of foreign particles in the air stream which might cause a malfunction in the various operating parts of the braking system. Further, the coating of the interior surface of the hollow axle is important for the axle assembly is a loaded carrying member and must be adequately treated to inhibit corrosiont 10~?4403 Summary of the Invention The invention provides a method of coating the interior surface of an axle assembly in which said axle assembly is a hollow tubular axle beam having a rectangular cross section and having a wheel mounting spindle at each end and the interior of said axle assembly provides a s~orage area for pressurized fluid, comprising the steps of blowing relatively high pressure air at about 90 psi through the int~rior of said axle to clear the interior of metal chips and the like, vertically displacing the axle assembly, washing said interior with a flow of steam at a temperature above 250F and a pressure of at least about 200 psi to remove any remaining foreign material including oil, drying the interior by introducing forced hot air around and through said axle from a fan-type heater, spraying the interior with a sprayable, non-peelable plastic coating, and drying said coating.
The spraying step preferably includes the inserting of a long spray head within the interior of the axle, wherein the spray head sprays in a 360 degree arc. The non-peelable plastic coating material is pumped to the spray head by an air no7zle pump at approximately 20 p.s.i., and sprayed to a thickness of approximately two mils.

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109~403 It is yet another object of the present invention to provide a method of coating the interior surface of an axle assembly wherein the blowing step includes blowing air into said interior at a nozzle pressure of approximately 90 p.s.i.
It is still a further object of the present invention to provide a method of coating the interior surface of an axle assembly wherein B said non-peelable plastic coating is Coverlac S-380~.
It is another object of the present invention to provide a method of coating the interior of a hollow axle of a vehicle axle assembly, the assembly having means for rotatably mounting a ground engaging wheel at each end of the axle, a fluid powered brake mechanism mounted to the axle adjacent each end thereof, each brake mechanism being operative when actuated to restrain rotation of a wheel rotatably mounted at that end of the axle, a relay valve body having a ~ounting flange formed integral therewith, means providing a source of pressurized fluid to the valve body, conduits connecting the relay valve body to the brake mechanisms at each end of the axle, relay valve means within the body and operable when actuated to supply fluid pressure from the source to the brake mechanism, a plurality of holes extending through the mounting flange, mounting flange is formed integrally with and at one side of the valve body, means for modulating the operation of the relay valve are mounted in the valve body, and the mounting flange and the modulating , ; means are spaced from one another, the valve body is comprised of an upper housing and a lower housing, the mounting flange is formed integral with one of the housings and surrounds a port opening into an inlet chamber, and means for modulating the operation of the relay valve are mounted in the other housing, comprising the steps of blowing air through the interior of the axle to clear the interior of metal chips and the like, washing the interior with a flow of steam to remove any remaining foreign material including oil~ drying the interior, spraying the interior with a sprayable, non-peelable plastic coating, drying the coating.
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: -4-109~403 It is a further object of the present invention to provide a method of coating the interior of a hollow axle of a vehicle axle assembly wherein said axle assembly includes a wheel speed sensor mounted at each end of the axle and adapted to generate electrical signals indicative of the angular velocity of a wheel rotatably mounted at that end of the axle, and the means for modulating the operation of the relay valve is comprised of electrical means mounted in the other housing and electrically connected to the wheel speed sensors.

Brief Description of the Drawings In the drawings, wherein like reference numerals designate like parts throughout:
Figure 1 is a perspective view of a vehicle axle assembly according to the present invention;
Figure 2 is a side elevation, partly in section, showing the relay valve and axle assembly of Figure l;
Figure 3 is a front elevation of the relay valve of Figures 1 and 2; and Figure 4 is a perspective view of the relay valve mounting member.
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Description of an Embodiment With reference to the drawings, Figures 1 and 2 show a trailer axle assembly generally designated by the numeral 10. The axle assembly 10 includes an axle 11 including a wheel mounting spindle 12 at each end thereof. A wheel hub and brake drum 14 is shown mounted to a spindle at ; one end of the axle 11. Brake mechanisms 15 and 19 are mounted at each ; respective end of the axle 11. The brake mechanism 15 includes a pair of wedge type actuators 16 which are driven by a pair of air motors 18, only one of which is shown in Figure 1. The brake mechanism 19 includes a pair of wedge type actuators within the brake drum 14 driven by a pair of air 3n motors 20.

109L~403 The interior or beam portion 21 of the axle 11 between the brake mechanisms 15 and 19 is formed as a hollow tubular member of rectangular cross section. A relay or brake control valve body 22 is mounted to a vertical wall 24, preferably the rearward facing wall, of the beam 21. The valve body 22 is comprised of an upper housing 25 and a lower housing 26. The housings 25 and 26 are secured together by bolts 28 passing through flange 29 of lower housing 26, the upper planar surface of which substantially bisects the valve body 22.
A mounting flange 30 is formed integrally with and at one side of the lower housing 26 of valve body 22. The mounting flange 30 is substantially triangular in shape and includes three mounting holes 31. The mounting flange 30 surrounds a port 32 opening into an inlet chamber in the lower housing 26. A pair of outlet ports 34 are provided, one at each side of the lower housing 26. A control or service pressure port 35 and an exhaust port 36 are provided to the upper housing 25.
The relay valve mechanism is provided internally of the valve body between the service pressure port 35 and the outlet ports 34 to control delivery of air pressure from the inlet chamber port 32 to the outlet ports 34 and then to the air motors 18 and 20 by the hose connections 38 : 20 and 40. Under normal operating conditions the relay valve mechanism isdirectly responsive to vehicle operator control pressure delivered to the - control or service pressure port 35 by a conduit 39.
The upper hcusing 25 also mounts a solenoid actuated valve internally of the control or service pressure port 35 and includes a computer chamber 41 closed by a cover plate 42. A computer and related circuitry is mounted within the chamber 41. The computer is powered by means of an electrical lead 44 which may be connected to the vehicle stop light circuit. The ~` computer is also electrically connected by leads 45 and 46 to wheel speed ~: sensors 48 and 49 respectively mounted internally of the brake mechanisms ; 30 15 and 19 at each end of the axle 11. The sensors 48, 49 respond to rotors carried by the wheels or hubs at each end of the axle and emit ~0~403 electrical signals indicative of the angular velocity of each wheel.
The computer monitors the s;gnals emitted by the wheel speed sensors and, if the signals indicate a wheel is about to lock, the computer actuates the solenoid internally of port 35 to modulate the vehicle operator applied brake pressure until the vehicle is brought to a stop or the incipient skid condition no longer exists.
The trailer axle beam 21 is sealed and the hollow interior serves as a reservoir of air pressure for delivery to the brake air motors 18 and 20. Air pressure is delivered to the hollow interior of axle beam 21 from a compressor by means of a hose 50 connected to a fitting 51 threaded through a wall of the axle beam. The air pressure is delivered to the relay or control valve body 22 through a beam outlet port 52 provided through the vertical wall 24 of axle beam 21.
It is the coating of the interior surface 23 of the trailer axle ll that is the primary thrust of the present invention. More particularly, the present invention is directed to a method that provides for the.efficient coating of the interior surface of the axle ll without the use of a number of dangerous and wasteful substances. The method contemplated by the present invention involves suitable preparation of the interior surface 23 of the axle ll by blowing and cleaning, culminating finally in the application of approximately two mils of a non-peelable plastic material. The first step of the method involves the blowing of air through the hollow inter;or with a suitable nozzle or the like.
The a;r may be service air as found in a typical manufacturing facility and may have a nozzle pressure of approximately 80-90 p.s.i. The blowing of such service air through the hollow interior of the axle will remove metal chips and other material therein whose presence may be caused by a number of the previous machining or manufacturing steps. The axle ll may be held ;n a horizontal or vertical position during the blowing step.
However, it has been found that the vertical displacement of the axle 10~4403 assists in the removal of such foreign matter from its interior. The next step involves the introduction of steam into the interior 23 of the axle 11. This particular step obviates the need for sandblasting which is typically utilized in the prior art methods. Sandblasting is both expensive and environmentally obnoxious. The steam is typically set at a temperature of between 250 to 300F and at a pressure of approximately 200 to 250 p.s.i. The steam will "wash" the interior surface 23 of the axle 11 and remove any remaining oil or foreign substances adhering to the interior surface 23. At this juncture, the interior surface should be substantially clean and free from foreign materials. To remove any remaining moisture condensed from the steam, the interior surface 11 is -then dried by the introduction of forced hot air therethrough. The forced hot air may be generated by a fan-type heater.
After the interior surface has been su;tably dried, it is ready for the application of a non-peelable plastic coating. A number and variety of plast;c coatings have been found satisfactory. However, the non-peelable plastic coating manufactured by Sprayta~t Corp., New York, New York, and designated as their Coverlac S-3808 component, has been found ; to be particularly satisfactory. The non-peelable sprayable plastic material is sprayed on the entire interior surface 23 of the axle 11 and may be applied by a spray wand such as manufactured by Vebilliss or Aero :; ~ B (their model Gunjet ~o. 4671). The sprayable plastic material need not be .~
preheated or preconditioned and is pumped to the spray wand by an airless pump as may be manufactured by Graco. The typical pressure for pumping the plastic component is 20 p.s.i. and the spray wand is adapted to spray through-out an arc of 360 degrees. The plastic coating is sprayed on the interior ' ~ surface 23 until approximately two mils thickness. Achieved uniformly . throughout, it has been found in an opened area that the drying time(tack-free) is five minutes. However, in an enclosed manufacturing facility, the drying time may be somewhat longer and may be shortened by an additional de~l~e~ l~6de m~r K

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drying step in which heated, forced air is introduced within the interior of the axle 11.
The above method no`t only results in h;gher production rates at lower costs, but also effects an efficient bond between the interior surface and the coating material.
Three studs 54 are threaded to and sealed against air leakage through the beam wall 24. The studs 54 are provided in a triangular pattern surrounding the beam outlet port 52. The studs 54 and port 52 are respectively spaced so as to be in axial alignment with the holes 31 and inlet port 32 of valve body 22.
A U-shaped mounting member or plate 56, as best shown in Figures

2 and 4 may be employed to reinforce the mounting flange 30. The mounting plate is preferably formed from steel and may be about the same thickness as the valve body mounting flange 30. A three-eighths inch thick mounting plate formed from SAE Type 1010 steel has proven to be satisfactory. The plate 56 includes a pair of legs 58, 59 joined together at one end by a cross member 60. Three mounting holes 61 are provided to the mounting plate 56. The mounting holes extend through the thickness of the plate 56 and are located one at each spaced apart end of the legs 58, 59 and one through the cross member 60. The mounting holes 61 are spaced for :~ axial alignment with the mounting holes 31 and the studs 54.
The valve body 22 is mounted to the axle wall 24 by aligning the ~ mounting flange holes 31 with the studs 54 and moving the mounting flange ; 30 into surface-to-surface contact with the beam wall 24. When the axle beam :: is utilized as an air reservoir, it is preferable to use an annular sealing element 33 seated in a groove 37 to prevent leakage between the mounting flange 30 and the beam wall 24. The mounting plate 56 is then positioned : with the legs 58, 59 on opposite sides of the inlet chamber of valve body 22 and the holes 61 aligned with the studs 54. The mounting plate 56 is then moved into contact with surface portions of the mounting flange 30 g 1.0~ 103 adjacent each of the holes 31. A washer and a nut 62 is then threaded to and tightened on each stud 54. The studs 54 and nuts 62 fix the valve body 22 to the axle beam 21 with the mount;ng flange secured between the mounting plat~ 56 and the beam wall 24.
This arrangement provides added strength to the assembly particularly the valve body mounting flange 30. The cross member 60 of mounting plate 56 abuts the flange surface adjacent the lo~er mounting hole 31 and effectively distributes bending loads developed in that portion of the flange by the valve body 22. The override solenoid, computer chamber 41, cover 42 and the computer and related circuitry are all mounted in the upper housing 25. As best shown by Figure 2 these components are all spaced from the mounting flange 30 and located on the opposite side of the upper planar surface of flange 29. These components and the portions of upper housing ~5 which enclose them present a substantial ~ass which is remote from the mounting flange 30 and acting as a cantilevered beam develops certain bending stresses in the mounting flange when the axle assembly is subjected to road shock and vibration. The steel mounting plate 56 prevents the flange 30 from moving relative to the mounting studs 54 and uniformly distributes the stresses induced when the cantilevered valve body 22 is subjected to road shock and axle vibration.
The flange reinforcing mounting plate thus provides a simple~
economical and effective means for mounting a brake control valve body directly to an axle without changing any components of the standard valve body. Moreover, since the mounting plate is secured to the valve body only at the mounting flange there is no need to disassemble the control valve or retest the valve after it is reassembled.
Once the axle assembly is complete, it constitutes a self-contained, anti-wheel lock axle assembly which can be readily mounted to a vehicle.
All that is required is mechanical connection to the vehicle suspension, fluid connection of the conduits 39 and 50 and electrical connection of the lead 44.

10~4403 The mounting plate may also be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. The foregoing description is therefore to be considered as illustrative and not restrictive, the scope of the invention being defined by the appended claims and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced thereby.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method of coating the interior surface of an axle assembly in which said axle assembly is a hollow tubular axle beam having a rectangular cross section and having a wheel mounting spindle at each end and the interior of said axle assembly provides a storage area for pressurized fluid, comprising the steps of blowing relatively high pressure air at about 90 psi through the interior of said axle to clear the interior of metal chips and the like, vertically displacing the axle assembly, washing said interior with a flow of steam at a temperature above 250°F and a pressure of at least about 200 psi to remove any remaining foreign material including oil, drying the interior by introducing forced hot air around and through said axle from a fan-type heater, spraying the interior with a sprayable, non-peelable plastic coating, and drying said coating.