Sheet metal shield and a wheel end assembly provided therewith

FIELD OF THE INVENTION

The present invention relates to corrosion protection of a driven or non-driven hub element used in automotive or industrial applications, where the hub element comprises at least a radially extending flange.

BACKGROUND TO THE INVENTION

In a typical wheel end assembly, a brake rotor is fitted to the wheel mounting flange of a flanged hub. The wheel rim is then mounted against the brake rotor and both are bolted to the wheel mounting flange. The flange-rotor interface is exposed to atmospheric corrosion from humid air and from salt water. The corrosion leads to the formation of rust on and between the contacting surfaces of the wheel mounting flange, brake rotor and wheel rim, meaning that a new brake rotor may need to be fitted. As a result of the corrosion, the flange and brake rotor can bond together, making disassembly costly. Moreover, the mounting flange surface becomes rough and uneven, leading to increased axial run-out if a new brake rotor is fitted. Excessive axial run-out causes brake judder, noise and vibrations, localized overheating of the brake rotor, and consequently, strict standards are applied. If the wheel mounting flange has suffered severe corrosion, a series of complex and costly measures must be taken to ensure that axial run-out specifications are complied with when a new brake rotor is fitted. It is therefore important to protect the flange surface from corrosion.

Several solutions have been proposed. For example, US 2007/010147719 discloses a hub unit where the wheel mounting flange is provided with an electro-corrosion preventive coating. The coating is provided by means of a plating process and comprises at least one layer of e.g. Zi-Ni which is then

passivated by means of chromating. This is a time-consuming and expensive process.

A solution that is widely used in automotive production lines is to apply an anti-corrosion paste between the wheel mounting flange and brake rotor. This solution, however, provides only short-term protection.

Consequently, there is still room for improvement.

SUMMARY OF THE INVENTION

An object of the invention is therefore to define a wheel end assembly that has long-lasting corrosion resistance. A further object of the invention is to define an economical and straightforward means of providing the wheel end assembly with corrosion protection, according to a method that is suitable for in-line integration in a manufacturing and assembly environment.

According to the invention, the aforementioned objects are achieved by a wheel end assembly comprising a flanged hub with at least a radially extending wheel-mounting flange, and further comprising a sheet metal shield that is mounted against the wheel-mounting flange. Thus, the sheet metal shield has a first surface that is in contact with the flange. To protect the wheel mounting flange from corrosion, at least the first surface of the sheet metal shield consists of a metal that has a higher galvanic potential than the metal from which the wheel mounting flange is made. In other words, in the presence of an electrolyte, the sheet metal shield will form an anode and the wheel mounting flange will form a cathode, whereby the shield will sacrificially corrode to protect the flange.

The present invention therefore also defines a sheet metal shield, comprising at least a disc portion that is adapted for mounting to a radially extending flange of a flanged hub, wherein at least a first surface of the sheet metal

shield consists of a metal having a higher galvanic potential than a metal surface against which it is mounted.

A sheet metal shield according to the invention may be provided in a wheel end assembly that comprises a flanged hub, a brake rotor and a vehicle wheel. The term brake rotor should be understood as a brake disc or a radially oriented portion of a brake drum. The shield may be mounted between the wheel mounting flange and the brake rotor or between the flange and a wheel rim of the vehicle wheel. A second surface of the shield is therefore in contact with an adjacent metal component. According to a second aspect of the invention, the second surface of the sheet metal shield consists of a metal with a higher galvanic potential than the adjacent metal component, in order to provide the adjacent metal component with sacrificial corrosion protection.

In a first embodiment of a sheet metal shield according to the invention, the shield is made of a sacrificial metal, i.e. a metal with a higher galvanic potential than the metallic surfaces it makes contact with. The flanged hub and brake rotor of a wheel end assembly are typically made of a steel alloy. Car wheel rims are commonly made from aluminium, while truck wheel rims are more usually made of a steel alloy. Thus, a suitable material for the sheet metal shield is zinc or a zinc-aluminium alloy such as ZnAM 5.

In a second embodiment, the shield is made from sheet steel with a sacrificial metal coating on one or both sides. In other words the material of the sacrificial metal coating has a higher galvanic potential than the metallic surfaces it makes contact with. Again zinc or a zinc-aluminium alloy, such as ZnAH 5, are suitable materials for the sacrificial metal coating.

A sheet metal shield according to the invention may have a thickness of between 0.01 and 3.0 mm, depending on the diameter of the flange to which it is mounted and the degree of robustness that is required. In heavy-duty

truck wheel end applications, for example, the shield may typically have a thickness of 1.0 - 2.0 mm. Thicknesses in excess of 3.0 mm are also possible. In car wheel end applications, the shield may typically have a thickness of 0.3 - 0.8 mm. When the shield is made of sheet steel coated with a sacrificial metal, the sheet steel may have a thickness of between 0.01 and 3 mm and the sacrificial coating may have a thickness of between 0.001 and 0.2 mm. Again, a larger sheet steel thickness may be selected, depending on the flange diameter and necessary robustness of the shield. The sacrificial metal coating preferably has a thickness of greater than 0.01 mm, to enable machining if necessary.

The thickness of the sacrificial metal is suitably selected on the basis of the corrosiveness of the application environment and the desired service life. The service life is determined by the length of time it takes until all of the sacrificial metal has oxidized. Thereafter, the flange will start to rust. In vehicle applications, a 0.025 mm layer of e.g. zinc on the shield results in a shield service life of approximately three years. Such a service life is consistent with the regular maintenance intervals for e.g. a brake disc. Needless to say, a greater thickness may be selected if a longer service life is required or if the application conditions are extremely corrosive.

By providing the wheel-mounting flange with a sheet metal shield that is electrochemically sacrificial, corrosion protection of the flange satisfying the industry standard ASTM B117 may be achieved. Materials such as zinc or a zinc-aluminium alloy can deliver this standard of corrosion protection. The aforementioned materials are also inexpensive and readily available. A further advantage of these materials is that the oxide layer which forms as the material corrodes does not cause a breakdown in the surface integrity of the material (unlike red rust). Thus, the solution according to the invention does not result in loosening of bolt torque when a brake rotor and/or wheel rim are fixed to the wheel mounting flange. The sheet metal shield also offers a satisfactory resistance to bolt load and has anti-fretting and failure-safe

properties, as well as having a satisfactory resistance to hot brake fluid, preservatives and cleaning fluids. The performance of the hub unit in the vehicle's wheel end is also unaffected.

Another advantage is that a sheet metal shield according to the invention may be retrofitted to the wheel mounting flange of existing vehicle hub assemblies.

A wheel end assembly according to the invention further comprises a bearing arrangement to support the flanged hub relative to a housing structure of the vehicle, e.g. a steering knuckle. The rotating part of the bearing arrangement is coupled to a shaft section of the flanged hub. The bearing arrangement may comprise one or more rolling element bearings or a preloaded bearing unit. The flanged hub may be adapted for inner ring rotation or outer ring rotation of the bearing arrangement. Likewise, the flanged hub may be adapted for driven and non driven applications. In the case of a wheel end assembly with a driven flanged hub and inner ring rotation of the bearing, for example, the bore of the hub's shaft section may be provided with female splines adapted to engage with male splines on the output shaft of a CV joint. Alternatively, an inboard side of the flanged hub may be provided with axial splines adapted to cooperate with corresponding axial splines on a bell section of the CV joint. Other types of torque transfer means are also possible, such as mating polygon connections or bolted connections.

In some examples of wheel end assemblies, the wheel-mounting flange of the flanged hub has an axial extension, known as a spigot or pilot section. The spigot facilitates proper centering of the brake rotor and the wheel rim during assembly. Corrosion protection on the outside diameter of the spigot is also desirable.

Thus, in a further development of the invention, the sheet metal shield comprises a radially extending disc portion and further comprises at least a

first axially extending tubular portion, where the disc portion is adapted for mounting against the flange and the tubular portion is adapted to fit over the outside diameter of the spigot. The spigot may comprise a brake-rotor centering section and a wheel-centering section of different diameter. Thus, in a further embodiment, the sheet metal shield further comprises a second axially extending tubular portion, where the first and second tubular portions are of different diameter.

Furthermore, a protective cover engaging an axially outermost tubular portion of the shield may be provided for enclosing the central opening in the shield. The protective cover may also serve to enclose electronic means comprising one or more sensors such as a load sensor and/or temperature sensor. The protective cover could also be made of a sacrificial metal or be provided with a sacrificial metal coating and thereby contribute to the cathodic protection of the flanged hub. In driven applications, the cover is preferably detachable, to enable the hub to be dismounted for servicing. In non-driven applications, the cover may be integrally formed with the shield. A sheet metal shield according to the invention may thus further comprise a second radially extending disc portion, disposed at an axial distance from the first disc portion.

The flanged hub of a wheel end assembly is typically provided with fixation means on the wheel mounting flange. The fixation means may be either stud bolts projecting out of the surface of the mounting flange, or threaded holes for receiving attachment bolts for bolting the shield, brake rotor and wheel rim to the mounting flange. The disc portion of the shield is therefore provided with openings corresponding to the bolt positions of the fixation means on the flange surface, so that the shield does not interfere with the mounting of a brake rotor and/or a wheel on the hub unit.

The shield may be held in position between the brake rotor and the flange only by the mounting forces there between. Alternatively, the shield may be connected to the mounting flange by gluing or some other adhesive means,

like a self-adhesive foil or a grease, or by a heat joining technique like welding, or by mechanical means. In a further example, in an embodiment where the shield comprises a tubular portion, the inside diameter of the tubular portion may be slightly smaller than the outside diameter of the spigot surface on which it is mounted. The shield can then initially be held in place by means of the resulting slight interference fit. A detachable connection between the shield and mounting flange has the advantage of allowing straightforward replacement of the shield.

The shield may be produced in a single piece by means of a cold-forming processes such as stamping and deep drawing. Alternatively, the one or more disc portions and tubular portions may be produced individually and then joined together by means of press fitting or by means of a welding process, such as laser or spot welding.

Thus, a sheet metal shield according to the invention and a wheel end assembly provided therewith has many advantages. The wheel mounting flange of the flanged hub is provided with long-lasting and robust corrosion protection that can be easily replaced or retrofitted. Moreover, the corrosion protection can be provided in a manner that is environmentally friendly, straightforward, inexpensive, and suitable for integration in a manufacturing and assembly line. In the case of a wheel end assembly, the provision of a sheet metal shield according to the invention enables compliance with axial run-out specifications for the duration of the shield's service life. Other advantages of the present invention will become apparent from the detailed description and accompanying drawings.

DESCRIPTION OF THE FIGURES In the following, the invention is described with reference to the accompanying drawings, in which:

figure 1a is a side view of a sheet metal shield according to a first embodiment of the invention; figure 1b is a front view of a shield according to figure 1 a; figure 2a is a side view of a sheet metal shield according to a second embodiment of the invention; figure 2b is a radial section through an embodiment of a wheel end assembly according to the invention; figure 3a is a side view of a sheet metal shield according to a third embodiment of the invention; figure 3b is a radial section through a further embodiment of a wheel end assembly according to the invention; figure 4 is a radial section through a still further embodiment of a wheel end assembly according to the invention; figure 5a is a side view of a sheet metal shield according to a fourth embodiment of the invention; figure 5b is a radial section through an embodiment of a wheel end assembly according to the invention provided with a shield as shown in figure 5a; figure 6 is a side view of a sheet metal shield according to a fifth embodiment of the invention.

DETAILED DESCRIPTION

Figure 1a and 1b respectively show a side view and a front view of a first embodiment of a sheet metal shield according to the present invention. The shield 1 comprises a disc portion 3 with a central opening 5 and mounting holes 7. The disc portion 3 is adapted to be mounted against a radially extending flange of a flanged hub, whereby the flange is made of a metallic material. The shield may be adapted to substantially cover the flange surface to which it is mounted, and the outer contour of the shield 1 can be circular or non-circular, i.e. adapted to follow the corresponding outer contour of the flange. The position of the mounting holes 7 in the shield 1 are

RECTIFIED SHEET (RULE 91) ISA/EP

adapted to correspond with the position of mounting holes in the flange surface.

According to the invention, at least the surface of the sheet metal shield that is mounted against the flange surface consists of a metal that has a higher galvanic potential than the metal from which the flange is made. In other words, the sheet metal shield has at least a sacrificial metal surface that provides the flange with sacrificial corrosion protection.

Figure 2a shows a second embodiment of a sheet metal shield, in which the shield 1 further comprises an axially extending tubular portion 9. The disc portion 3 is again adapted to fit against the flange surface of a flanged hub and the tubular portion 9 is adapted to fit over and against an axially extending portion of the flanged hub, which axially ending portion is made of a metal material. According to the invention, the surface of the tubular portion in contact with the axially extending portion of the flanged hub also consists of a metal that has a higher galvanic potential than the metallic surface it makes contact. An example of a wheel end assembly according to the invention, provided with a shield as shown in figure 2a, is illustrated in figure 2b.

Figure 2b shows an example of wheel end assembly for e.g. a truck, where the assembly comprises flanged hub 11 provided with a sheet metal shield according to the invention. The flanged hub 11 comprises a shaft section 13, a radially extending flange 15 for the mounting of a vehicle wheel and further comprises a spigot 17 for centering the wheel on the flanged hub 11. The shaft section 13 of the flanged hub 11 is coupled to the rotating part of a bearing arrangement. In the embodiment shown, the bearing arrangement consists of two separate rolling element bearings 23, the bearings comprising an inner ring 25, an outer ring 27 and rolling elements 29 disposed therebetween.

The flanged hub 11 is made of a suitable metal material and is further provided with a sheet metal shield 1. The disc portion 3 of the shield covers the flange surface of the wheel mounting flange 15 and the tubular portion 9 of the shield covers an outside diameter of the spigot 17. The wheel end assembly further comprises a brake rotor 21 , which is a brake drum in the illustrated example, and a wheel that is attached to the wheel mounting flange 15 via bolts 20 and centred on the spigot 17. Thus, an outboard side of the disc portion 3 and a radially outer surface of the tubular portion 9 are in contact with surfaces of a wheel rim 19. The wheel rim 19 may be made of aluminium or a steel alloy.

According to a first aspect of the invention, at least the surfaces of the shield that are in contact with surfaces of the flanged hub 11 consist of a sacrificial metal having a higher galvanic potential than the contacting metal surfaces of the flanged hub 11. According to a second aspect of the invention, also the surfaces of shield that are in contact with the wheel rim 19 consist of a sacrificial metal having a higher galvanic potential than the contacting metal surfaces of the wheel rim 19.

In a first embodiment, the sheet metal shield is made of the sacrificial metal. The shield 1 may suitably be made of zinc or a zinc aluminium alloy such as ZnAH 5. In a second embodiment embodiment, the shield consists of sheet steel that is coated on both sides with a sacrificial metal such as zinc or a zin- aluminum ally such as ZnAM 5.

A sheet metal shield according to the invention may have a thickness of between 0.01 and 2.5 mm. When the shield is made from sheet steel coated on one or both sides with a sacrificial metal coating, the sheet steel may have a thickness of between 0.1 and 2.0 mm, and the sacrificial metal coating may have a thickness of between 0.001 and 0.2 mm. Preferably, the coating thickness exceeds 0.01 mm, to enable the coated surface to be machined if necessary. The thickness of the shield is suitably selected depending on the

application, i.e. the size of the mounting flange and the required robustness of the shield. The thickness of the sacrificial metal coating is suitably selected on the basis of the corrosiveness of the application environment and the required service life of the shield.

The wheel end assembly shown in figure 2a is an example of an assembly adapted for driven rotation of the flanged hub 11 , where the flanged hub is supported by a bearing arrangement adapted for outer ring rotation. The flanged hub may also be adapted for non-driven applications and for driven applications where the bearing arrangement has inner ring rotation. In the example shown in figure 2a, the brake rotor 21 is a brake drum and the wheel mounting flange 15 is integrally formed with the brake drum. The brake drum may also be joined to the flange section. The brake rotor can also be a separate part, like a brake disc, and, likewise, the wheel mounting flange 15 can be a separate part that is coupled to the shaft section 13 of the flanged hub 1 1. Other examples of sheet metal shields and flanged hubs according to the invention are also possible.

Figure 3a shows a third embodiment of a sheet metal shield according to the invention. The shield 1 comprises the disc portion 3, a first tubular portion 9 and a second tubular portion 31 , where the second tubular portion 31 has an outside diameter equal to the diameter of the disc portion 3. Such a shield may be mounted on a flanged hub that forms part of a wheel end assembly as illustrated in Fig 3b.

The wheel end assembly shown in figure 3a is an example of car wheel end and comprises a flanged hub that is provided with a sheet metal shield as shown in figure 3a. The flanged hub 11 comprises a shaft section 13, a wheel mounting flange 15 and a spigot 17. In this example, the wheel end assembly further comprises a separate brake rotor 21 that is mounted to the wheel mounting flange 15 and further comprises a wheel rim 19 that is attached to the brake rotor 21 and wheel mounting flange 15 via bolts 20. Suitably, the

spigot 17 comprises a first axially extending portion, which is adapted to centre the brake rotor 21 , and comprises a second axially extending portion, which is adapted to centre the wheel rim 19. The outside diameter of the first axially extending portion may be larger than the outside diameter of the second axially extending portion of the spigot 17.

The flanged hub 11 in this example is driven by a flanged shaft 33 of a constant velocity joint 32. The shaft section 13 of the flanged hub 11 is coupled to an inner ring of a bearing unit 23, which may be a double-row angular contact bearing, tapered roller bearing or some other suitable rolling element bearing. The wheel end assembly further comprises a first sheet metal shield 1 , which is mounted on the brake-rotor centering section of the spigot 17, between the wheel mounting flange 15 and the brake rotor 21. The brake rotor 21 in this example comprises an axially extending portion that fits over an outside diameter of the wheel mounting flange 15. Thus, the first sheet metal shield 1 comprises a tubular portion 31 with an inside diameter substantially equal to the outside diameter of the flange 15, whereby a radially inner surface of the tubular portion 31 is contact with the flange 15 and a radially outer surface of the tubular portion is in contact with the brake rotor 21. According to the invention, also the surfaces of the tubular portion 31 consist of a metal with a higher galvanic potential than the metallic surfaces they are in contact with. Thus, the first shield 1 provides sacrificial corrosion protection to the flange 15, the brake rotor 21 and the spigot 17. As will be understood, if the radially outer surface of the flange (15) has a non- circular geometry, the covering tubular portion 31 of the shield 1 may have a corresponding non-circular geometry.

The wheel end assembly shown in figure 3b further comprises a second sheet metal shield 1 ' according to the embodiment shown in figure 2a, which is mounted on the wheel centering section of the spigot 17, between the brake rotor 21 and the wheel rim 19. Thus, the second sheet metal shield 1 '

provides sacrificial corrosion protection to the brake rotor 21 , the wheel rim 19 and the spigot 17.

A wheel end assembly according to the invention may also be provided with a third sheet metal shield. Figure 4 illustrates an example of a truck wheel end assembly, comprising a flanged hub provided with sheet metal shields according to the invention. The flanged hub 11 comprises a first sheet metal shield 1 , of the type shown in figures 1 a and 1 b, mounted to an inboard- facing side of the flange 15 at the interface between the flange and a brake rotor 21. Thus, the first shield 1 provides sacrificial corrosion protection to the brake rotor 21 and the inboard side of the wheel mounting flange 15. The flanged hub 1 1 further comprises a second shield 1 ', of the type shown in figure 2a, whereby the disc portion is mounted against an outboard- facing side of the flange 15 at the interface between the flange and a wheel rim 19 (of a twin wheel). The tubular portion of the second shield 1 ' is suitably mounted over a wheel-centering section of the flanged hub 11. Thus, the second shield 1 ' provides sacrificial corrosion protection to the wheel rim 19, the wheel centering section of the flanged hub 11 and the outboard side of the wheel mounting flange 15.

In the illustrated example, the flanged hub 11 is driven by means of a flanged shaft 33. The flange of the flanged shaft is bolted to a shaft section 13 of the flanged hub 11 , at an outboard end face 35 of the shaft section 13. Suitably, a third shield 1 ", of the type shown in figures 1 a and 1 b, is mounted to the outboard end face 35 of the shaft section 13 at the interface with the flange of the flanged shaft 33. The third shield 1" provides sacrificial corrosion protection to the shaft section 13 of the flanged hub 11 and to the flange of the flanged shaft 33. The wheel end assembly as a whole is therefore provided with excellent corrosion protection by means of the first, second and third sheet metal shields.

A further embodiment of a sheet metal shield according to the invention is shown in figure 5a. Here, the shield 1 comprises a disc portion 3, a first tubular portion 9 and further comprises a second tubular portion 36, whereby the diameter of the second tubular portion 36 is smaller than the diameter of the first tubular portion 9. The shield 1 may be made of one piece, e.g. by means of stamping and deep-drawing, or the individual sections that make up the shield - the disc portion 3, first tubular portion 9 and second tubular portion 36 - may be joined together by means of press fitting or a heat joining process like laser welding or spot welding.

Figure 5b illustrates an example of a wheel end assembly comprising a flanged hub that is provided with a shield of the type shown in figure 5a. The wheel end assembly in this example is for a driven wheel of a car, whereby the bore of the flanged hub 11 is provided with splines adapted to engage with mating splines on the output shaft of a constant velocity joint 32. The shaft section 13 of the flanged hub 11 is suitably coupled to the rotating part of a bearing, which in this example is a two-piece inner ring 25 of a double- row angular contact bearing unit 23. The wheel end assembly further comprises a brake rotor 21 and a wheel rim 19, which are centred on corresponding portions of a spigot 17 of the flanged hub 11 , and which are bolted to a wheel mounting flange 15. To provide the spigot 17 and flange 15 with corrosion protection, the flanged hub 11 is suitably provided with a sheet metal shield 1 of the type shown in figure 5a, whereby the shield 1 comprises a first tubular portion 6 and a second tubular portion 36 that fit over the corresponding portions of the spigot 17. Thus, the first tubular portion 9 serves as a brake rotor centering section and the second tubular portion 36 serves as a wheel rim centering section. Depending on the design of the spigot, the second tubular portion 36 may have a smaller diameter than the first tubular portion 9 of the shield. If further protection of the flange is needed, the shield 1 may comprise a further tubular portion with an inside diameter substantially equal to an outside diameter of the flange 1. The further tubular portion is then adapted to cover the outside diameter of the

wheel mounting flange 15 (such as shown by the tubular portion 31 in figures 3a and 3b).

With reference to figure 5b, the bore of the flanged hub 11 may be shielded by a protective cover 37, to prevent the entry of moisture and provide the assembly with further protection against corrosion. In driven applications, the protective cover 37 is preferably a detachable element, to enable the hub 11 to be serviced. The protective cover 37 may therefore be adapted to fit over and engage with an axially outermost portion of the shield, or the axially outermost portion of the shield may be provided with a rim that is adapted to engage with a corresponding lip on the protective cover 37. Moreover, a detachable protective cover 37 may be equipped with sensors, such temperature and/or load sensors, and enclose electronics for controlling the wheel end functions and/or the dynamic stability of the vehicle.

In non-driven applications, the protective cover 37 may be non-detachably connected to the shield 1 by means of e.g. laser welding. In a further embodiment, the cover 37 may be integrally formed with the shield. An example of this embodiment is shown in figure 6, where the shield 1 is closed at one axial end by a second disc portion 37, which acts as the protective cover.

For aesthetic reasons, the outboard-facing surface of the protective cover 37 could be provided with a coloured coating. Alternatively, a manufacturer's logo or identification code could be provided on this surface. Such a coloured coating, logo or code may be provided on the protective cover 37, regardless of whether cover is a detachable or non-detachable element or is integrally formed with the shield.

Above, the invention is described with reference to some preferred embodiments. However, a sheet metal shield according to the invention may be executed in many embodiments and have a geometry that is adapted to

the surface geometry of the flanged hub to which it is mounted. Similarly, although the embodiments of the invention have been described only with reference to automotive applications and wheel end assemblies comprising a flanged hub, it should be understood that a sheet metal shield according to the invention may be mounted to any kind of flanged hub. For example, the flanged hub of a large pump assembly operating in corrosive conditions could advantageously be provided with a sheet metal shield according to the invention. Thus, variations of the embodiments of the invention described may be performed without departing from the scope of the invention defined in the claims.

Reference numerals

1 , 1 ', 1" sheet metal shield

3 disc portion of shield 5 central opening in shield

7 mounting holes in shield

9 first tubular portion of shield

11 flanged hub

13 shaft section of flanged hub 15 radially extending flange of flanged hub

17 axially extending portion of flanged hub

19 wheel rim

20 fixation bolt

21 brake rotor 23 rolling element bearing

25 bearing inner ring

27 bearing outer ring

29 rolling elements

31 tubular portion of shield to fit over OD of flange 32 constant velocity joint

33 flanged shaft

35 outboard end face of shaft section

36 second tubular portion of shield

37 protective cover