SAF SKRS 9042 SK 500 plus Operating instructions

SK RS 9042 - SK 500 plus
Maintenance and
Repair Manual
Service
Edition 01/2006

2
Vehicle information
Manufacturer.................................................................................................................................
Address...........................................................................................................................................
Body type.......................................................................................................................................
Chassis no.......................................................................................................................................
Year of manufacture ....................................................................................................................
Registration, date-in-service.........................................................................................................
Identification of axles without type plate
Production No. of axle on right of stub axle as seen in
direction of forward travel.
Type plate for axle identification
(on the inside of the trailing arm or axle beam)
Spare parts service
for SAF axles and suspension systems
When ordering spare parts, quote correct
axle identification serial no., refer to the
axle type plate.
Please enter the vehicle identification
figures in the type plates shown below
so that correct information is available
when required.
96
195
047

Spare part illustration and spare part designation
SK RS 9042 - SK 500 plus 10-11
SAF axle identification 2
Repairing the brakes 12-22
Repairing the wheel bearings
Replacing the wheel bearing grease 23-25
E) Installation instructions
D) Spare part illustrations/spare part designation
C) Maintenance instructions
Maintenance instructions for SK RS 9042 - SK 500 plus 8
Maintenance schedule for SK RS 9042 - SK 500 plus 9
3
Contents
Page
This manual is intended for the technical workshop personnel responsible for
maintenance and repair.
A) Component description 4-6
B) General service instructions for SAF axles and suspension units 7
Adjustment of S-cam brakes with manual slack adjusters 26
Adjustment of HALDEX automatic slack adjusters 27
Adjustment of S-ABA automatic slack adjusters 28
F) Slack adjuster
G) Track control 29-30
H) Service tools 31-32
I) Tightening torque in Nm 33
The item numbers indicated are given only for identification and to distinguish between different versions.
Use the part numbers from the valid spare parts documents for identification of spare parts.
SAF axles and suspension units are subject to continuous further development; the data and drawings
contained in the manual may therefore differ from the details given in the operating permit.
The contents of the manual does not constitute the basis for a legal claim.
Reprinting, reproduction or translation in whole or in part is not permitted.
The issue of this publication invalidates all earlier maintenance and repair manuals.

4
A) Component Description
The components of the SAF axle Types SK 500 plus have important technical details which distinguish them
from other axle types:
– Great ease of installation
(e.g. only 1/4 of the working time is now required for brake repairs)
– Long wheel bearing grease change intervals of 500,000 km or 60 months’ operation
– Favourable lubrication intervals for the camshaft bearing at each brake lining change, but not later than
every 12 months
– Approx. 40% less individual components in the brakes
– Wheel bearing clearance adjustment is required as in the past
Overview of the Components
Hub cap with snap fit:
Removal and fitting is quick and easy; simply lever off and push on.
New typePresent type
New typePresent type
Wheel hub:
A compact unit of hub with two different sized wheel bearings and seal rings.
The wheel bearings are filled with a longlife grease and sealed.

5
A) Component Description
Wheel bearing:
Thanks to the protected installation of generously dimensioned wheel bearings, long service
lives can be achieved.
Grease changing at brake repairs is no longer necessary.
After 500,000 km or after 60 months’ operation, the following 2 procedures are possible:
1) Inspection of the wheel bearing for further serviceability with grease change and replacement of
the seal rings.
2) Replacement of the complete wheel bearing assembly with seals and long-term grease packing.
The wheel hub can continue to be used.
New typePresent type

6
A) Component Description
Wheel bearing clearance
The wheel bearing clearance has to be adjusted as in the past.
Axle nuts
The axle nuts have a right-hand thread on both sides. The wheel
hub is secured with a lock nut.
Brake shoes
The brake shoes are each supported spherically on a ball and are
held by a spring clamp. Only one return spring is required for the
return of the brake shoes. The brake shoe cam rollers are guided
exactly in the specially machined S-cam profile.
Brake linings
Two different asymmetrically formed lining segments are riveted
onto the brake shoes. The thicker end of the lining is installed on
the S-cam side (cam roller).
As a result of this scythe-shaped brake lining contour, uniform maxi-
mum wear of the brake lining over the whole surface is achieved
during normal operation.
The brake linings have an embossed groove on the end surfaces
which indicates the maximum permissible lining wear.
Camshaft
The camshafts are mounted in the brake carrier and in the slack
adjuster in a compact bearing which allows quick replacement. Both
bearings have grease nipples and must be regresed every 12 months.
Both bearings have a long-life lubrication and are protected by seal
rings and rubber sleeves against the ingress of dirt and splash water.
On the slack adjuster end the camshaft has a milled groove and a
slip-on indicator for visual checking of the brake lining wear.
When the wear indicators have reached a horizontal position, an
inspection of the brake lining thickness must be carried out.
Max. permitted radial play: 2 mm
Inspection of the brake lining thickness
During maintenance work, the thickness of the brake linings can be
inspected at two sight holes in the rear cover plate.

7
B) General service instructions
Please observe the following safety instructions in order to maintain the operational and road safety
of your SAF axles and suspension systems:
1. The wheel contact surfaces between the wheel disc and wheel hub and the wheel nut contact surface at
the wheel disc must not be additionally painted. The contact surfaces must be clean, smooth and free
from grease. Failure to observe this may result in the wheel coming loose. Any additional instructions of
the wheel manufacturer must also be observed.
2. Only the wheel and tyre sizes approved by the trailer builder may be used. The tyres must always have
the specified inflation pressure.
3. The brake systems of the tractor and the trailer/semi-trailer must be synchronised by means of a
tractor/trailer brake synchronisation not later than 5,000 km after the initial start of operation of the
trailer/semi-trailer in order to ensure a safe and uniform braking behaviour and uniform brake pad wear.
Tractor/trailer brake synchronisations should be carried out by appropriately qualified and equipped
brake workshops.
The use of an additional braking system, such as a trailer anti-jackknife brake is forbidden by law on
vehicles with type approval after January 1999.
4. Before starting a journey, ensure that the maximum permissible axle load is not exceeded and that the
load is distributed equally and uniformly.
5. On trailers with air suspension, ensure that the air bags are completely filled with air before starting the
journey. Incompletely filled air bags may result in damage to axles, suspension, frame and superstructure
and impair road safety.
6. Ensure that the brakes are not overheated by continuous operation.
With drum brakes, overheating can result in a hazardous deterioration in the braking efficiency.
With disc brakes, overheating can result in damage to surrounding components – in particular the wheel
bearings. This can result in a significant deterioration in road safety, e.g. failure of wheel bearings.
7. The parking brake must not be immediately applied when the brakes are hot, as the brake discs and
brake drums may be damaged by different stress fields during cooling.
8. Use the supports provided when loading and unloading in order to avoid damage to the axle.
9. Observe the operating recommendation of the trailer builder for off-road operation of the installed
axles and suspension systems.
The SAF definition of OFF-ROAD means driving on non-asphalted / non-concreted routes, such as e.g.
gravel roads, agricultural and forestry tracks, on construction sites and in gravel pits.
Off-road operation of SAF axles and suspension systems not designed for the purpose may result in
damage and hence to an impairment of road safety.
10. SAF axles and suspension systems require continuous care, service and maintenance in order to maintain
operational and road safety and to be able to recognise natural wear and defects in good time.
The daily inspection of the trailer for road safety before starting the journey is one of the driver’s
obligations.
SAF recommends that at least the inspections and maintenance operations described on page 8 should
be carried out.
We recommend the use of original SAF spare parts.
A close-knit service network of SAF partner companies is available for the technical support of the SAF axles
and suspension systems and for the supply of original SAF spare parts (see rear cover or on the Internet under
www.saf-axles.com).
Updates will be published as necessary on the Internet under www.saf-axles.com.

8
C) Maintenance instructions
SK RS 9042 - SK 500 plus
Vehicles with long standing periods: service at specified time intervals
Vehicles used under extreme conditions: service at suitably reduced intervals
Maintenance intervals
whichever comes first
Mileage intervals >
Time intervals >
After first
5,000 km
or every
30,000 km
every
150,000 km
After first
month every
3 months
every
75,000 km
every
6 months
every
12 months
Periodic checks
Check and adjust hub end-float (if required) after every brake
lining replacement.
Pack wheel bearings with fresh grease after 500,000 km or
60 months, whichever comes first.
Lubricate camshaft bearings after every brake lining replacement,
however, at least every 12 months.
The U-bolt must be tightened once only within the first 5,000 km
after the first loaded test-drive.
– Perform general annual inspection
(brakes, air bags, tyres, etc.)
– Perform general annual safety check
(tractor/ (semi-) trailer brake compatibility, ABS etc.)
Note: Be sure to retighten wheel nuts to the prescribed torque
after the first 50 km and 150 km (and after every wheel removal).
Mechanical check
Visual and safety inspection
Special service conditions
••
•
Warranty claims will only be accepted as long as the operating and maintenance instructions have been
complied with and if SAF approved spare parts have been fitted.

9
C) Maintenance instructions
SK RS 9042 - SK 500 plus
Adjusting the wheel bearing clearance:
Tighten axle nut W.A.F. 85 (22) to a torque of 150 Nm,
turning the wheel hub at the same time.
Back off the axle nut by 2 1/2 holes of the locking collar
(23).
Push on the locking collar and secure the hub nut with
dowel.
Tighten the lock nut (24) to a torque of 400 Nm.
Check that the wheel bearing rotates freely and without
excessive end float. The wheel must rotate freely and with-
out resistance and no end float should be felt at the wheel
rim. Repeat the adjustment, if necessary.
Lubricant specification:
Wheel bearings:
SAF Part No. 4 387 0011 05
Camshaft:
SAF Part No. 4 387 0011 05
Stub axle:
SAF Part No. 4 387 0015 06
SAF fitting paste
Brake anchor bracket ball:
SAF Part No. 4 387 0007 00
Copper paste
Hub nut tightening
Assembly tools SAF parts no.
Hub nut spanner W.A.F. 85 2 012 0023 01
Puller for wheel hub 4 434 3822 00
Brake shoe clamping device 3 349 1001 00
Brake drum fixing flanges 3 434 1060 00
Wheel bearing installation drift 3 434 3308 00
Mounting drifter for cassette seal 3 434 1036 00
Brake drum / brake lining
refacing stages in mm
BRAKE type SNK 420
Max. permissible turned brake drum bore: 424.0 mm
Brake drum bore with max. permissible wear: 425.0 mm
SAF approved brake linings: BERAL 1541, BREMSKERL 6386
Turn new brake linings to brake drum bore dimension + 0.3 mm.
When renewing rivets, observe the manufacturer’s instructions regarding the brake lining form
(see leaflet enclosed in pack).
Normalmaß
1. Rep.-Stufe
2. Rep.-Stufe
d
0
d
1
d
2
Brake linings Rivets
420.0 422.0 424.0
DIN 7338
rivet
number per axle
SNK 420 d0-420.0 d1-422.0 d2-424.0
x 180 1 057 0060 00 20.6 21.6 22.6
1 057 0061 00 20.0 21.0 22.0
x 200 1 057 0066 00 20.6 21.6 22.6
1 057 0067 00 20.0 21.0 22.0
64 B 8 x 15
Nominal size 1st oversize 2nd oversize
Brake SAF parts no.
size brake lining
4
nominal size
1st oversize
2nd oversize

10
D) Spare part illustrations
SK RS 9042 - SK 500 plus
Torque wrench settings
Use a torque wrench.
The use of impact wrenches
is not accepted.
Wheel nuts:
Spigot-hub-centred fixing:
M 22 x 1.5 / 600 Nm
Bolt-centred fixing:
M 22 x 1.5 / 430 Nm
U-bolts:
(diagonally in three stages)
M 22 / 650 Nm
Shock absorber:
M 24 / 400 Nm
Type plate

11
D) Spare part designation
SK RS 9042 - SK 500 plus
Item Parts designation Item Parts designation
01 Axle beam assembly
including items 3 - 25
3 Spherical mounting plate
4 Protective plug for ABS
5 Ball
6 Compact bearing,
brake carrier side
6.1 Riffle bolt
6.2 Lock nut
010 Camshaft bearing assembly
linkage adjustment side
including items 11, 15, 18
11 Compact bearing,
linkage adjuster side
15 Pinch bolt
18 Bellows
18.3 Brake lining wear gauge
22 Hub nut with dowel
23 Locking collar
24 Lock nut
25 Mounting plate for MB cylinder
27 Wheel hub (present type)
27.1 Wheel hub (new type)
29 Brake drum
30 Wheel bolt assembly
including items 31 - 34
31 Riffle bolt
34 Wheel nut with pressure plate
35 Taper roller bearing
36 Taper roller bearing
37 Unitised seal
38 Inner seal ring
38.1 Protective plug
38.2 Outer seal ring
39 O-ring
40 Wheel cap, complete
including items 39 - 41
41 Plug
059 Brake assembly
including items 64, 74 - 75
64 Brake shoe assembly
including items 65, 71 - 73
65 Brake shoe with item 66
66 Cam roller
70 Brake lining set
including items 71 - 73
71 Brake lining, cam roller side
72 Brake lining, ball side
73 Rivet
74 Clamp
75 Return spring
77 Exciter
78 ABS rod sensor
80.1 Protective hose
80.2 Clamp
80.3 Circlip
89 Mechanical slack adjuster
081 Camshaft assembly (LH)
including items 18.3, 85.1 - 88.1
082 Camshaft assembly (RH)
including items 18.3, 85.1 - 88.1
85 Disc spring
86 Clamp
87 Washer
88 Washer
88.1 Clamp
with automatic adjustment
89.1 Automatic slack adjuster
89.2 Anchor plate, RH
89.3 Anchor plate, LH
90 Return spring
091 Dust cover assembly
including items 92 - 99
92 Dust cover, RH
93 Dust cover, LH
94 Plug
95 Cable clamp
96 Hex bolt
97 Clamp
98 Plug
99 Rubber grommet, ABS
When ordering spare parts quote correct axle identification serial no., refer to the axle type plate.

12
E) Installation instructions
Repairing the brakes
Removing and installing the wheel hub
Park the vehicle on level, solid ground and chock the wheels to
prevent the vehicle from rolling away
Lift the axle using a jack. Do not position the jack in the middle of
the axle.
Completely release the wheel brake by turning the adjusting screw
on the slack adjuster until cam and brake shoes are in the end
position.
Lever the hub cap (SAF Part No. 1 434 1041 00) off the wheel hub
using one of the recesses around the circumference of the hub cap.
Loosen the lock nut and unscrew from the stub axle.
Axle nut wrench: SAF Part No. 2 012 0023 01.
Remove the locking collar.
Unscrew the axle nut.
Pull off the wheel hub.
The complete wheel hub unit can be easily pulled off the stub axle.
If the bearing races tilt on the stub shaft, the hub unit can be pulled
off using a normal workshop puller or SAF Part No. 4 434 3822 00.

13
E) Installation instructions
Brake drum cleaning:
The brake drum may only be cleaned using a dry cleaning material.
Liquid cleansers, high-pressure cleaners or machine cleaning are not
permitted. With this type of cleaning there is a danger of cleansing
fluid entering the wheel bearing with a consequent failure of the
wheel bearing lubrication.
Disassembling the brakes
Lever the spring clip out of the retainer in the brake shoe using a
screwdriver.
Remove the spring clip.
Pull the upper brake shoe sideways over the cam and ball pivot
point and then remove both brake shoes from the brake carrier.
Inspecting the camshaft
Push the camshaft backwards and forwards firmly in the compact
bearing and measure the radial clearance.
Max. permitted radial play: 2 mm
If the maximum permissible radial clearance is exceeded, the cams-
haft must be removed and the compact bearing on the brake carrier
must be replaced.
Removing and installing the camshaft
Remove the slack adjuster.
Position of camshaft bearing

14
E) Installation instructions
Remove the spring clip from
the groove in the camshaft
and pull the camshaft com-
pletely out of the bearing.
Arrangement and installation
position of the camshaft
bearings, see drawing on
page 13.
Remove the bolts from the compact bearing and replace with a
new bearings (see page 10, item 81 with parts 85.1 - 88.1, and
item 10 with parts 11, 15 and 18).
After installation of th e new
compact bearing, the cams-
haft must rotate freely. Insert
the bolts and fit the nuts.
Tightening torque for the bolts on the compact bearing:
- Brake side 40 Nm
- Slack adjuster side 35 Nm

15
E) Installation instructions
Replace the complete compact bearing assembly on the slack adjuster.
Coat the splines on the camshaft and the splines on the slack
adjuster with copper paste (SAF Part No. 4 387 0007 00).
Suitable greases, see chapter “Maintenance instructions”.
Push washer and new sealing
sleeve onto the camshaft.
Insert the camshaft into the
bearings and secure in position
with the circlip.
Align the compact bearings with the camshaft, tighten the mounting
bolts and check the camshaft for free rotation.
If necessary, correct the position of the compact bearing relative to
the slack adjuster again.
Push on both seal sleeves until they contact the compact bearing on
the slack adjuster side.
Install the slack adjusters and wear indicators, place both cover
plates and secure on the axle tube with clamps.
Pack the compact bearing in the brake carrier and on the slack
adjuster with grease using a grease gun until grease emerges at
the end of the bearing.
Turn the camshaft through 360º several times.
Check that the bearing is completely lubricated and that the cams-
haft turns easily.
Lubrication intervals for the camshaft bearing, see chapter
“Maintenance instructions”.

16
E) Installation instructions
Brake linings
Original dimensions and wear limits, see table in chapter
“Maintenance instructions”.
Two different brake linings are riveted onto each brake shoe.
The lining contour tapers towards the ball side.
The thicker end of the brake lining is riveted on the roller side
(S-cam).
Corrosion-proofed steel rivets are used for securing the linings.
The brake linings have a monitoring shoulder on the face end indi-
cating the brake lining type approved by SAF and the wear limit for
the minimum brake lining thickness.
Only brake linings of the same quality may be installed on the same
axle.
Observe the approved rivet quality (see table in chapter
“Maintenance”).
Replacement of the brake lining
Clean all parts and inspect for wear. Inspect the brake drum for
wear and turn down to the next repair stage, if necessary (see table
in chapter “Maintenance instructions”).
Remove the brake lining from the brake shoe.
Thoroughly clean the mounting surface for the brake lining on the
brake shoe; grind slightly, if necessary.
Carefully remove any corrosion from the lining plate. Protect the
contact surface against corrosion with a thin coating of zinc dust
primer.
Replace the brake linings according to the repair stage of the brake
drum (see table in chapter “Maintenance instructions”).
Observe the position of the different brake lining segments.
The thicker end of the brake lining is riveted on the roller side
(S-cam).

17
E) Installation instructions
The brake lining must contact the brake drum over its full surface.
The corners of the brake lining must not be broken and the lining
must not be cracked at the rivets.
Required riveting force: 25,000 N
Read off the required working pressure on the setting plate of the
rivetter and set the pressure at the pressure gauge.
Observe the rivetting sequence 1 - 8 for each brake lining half.
Brake drum
Brake drum diameter.
Permissible wear limits, see table in chapter “Maintenance instruc-
tions”.
Brake drum cleaning:
The brake drum may only be cleaned using a dry cleaning material.
Liquid cleansers, high-pressure cleaners or machine cleaning are not
permitted. With this type of cleaning there is a danger of cleansing
fluid entering the wheel bearing with a consequent failure of the
wheel bearing lubrication.
Inspecting the brake drum
Removing and installing the brake drum
Inspect the brake surface of the brake drum closely for further
serviceability.
Brake drums with fine hairline cracks in the contact surface can con-
tinue to be used. If the contact surfaces of the brake drums exhibit
deep scoring, the drums must be turned down. If cracks are still
visible after turning down, replace the brake drums.
Measure the brake drum diameter and turn down to the next repair
stage, if necessary. When the maximum permissible brake drum inside
diameter is reached, the brake drums must be replaced.
Permissible wear limits, see table in chapter “Maintenance instruc-
tions”.

18
E) Installation instructions
Note:
The compact wheel bearing units are not removed when turning
down the brake drum.
Centre wheel hub on the brake drum lathe using clamping device,
SAF Part No. 3 434 1060 00
Further machining of the brake drum can then be carried out as nor-
mal in the workshop.
Replacing the brake drum
To remove the brake drum from the wheel hub, drive out all wheel
bolts from the wheel hub using a hammer.
Before assembling the wheel hub and brake drum, remove any
corrosion from the contact surfaces.
Drive the wheel studs into the brake drum flange until they are
flush with the inner surface using a normal workshop drift.
Ensure that the twist lock engages correctly.
The circlips (33) are no longer required.
If necessary, the wheel studs can also be correctly positioned by
pulling in using a wheel nut.
Ensure that the ABS exciter ring is in the correct operating position.
Installing the brake shoes
Check the proper mounting seat of the two balls in the brake carrier.
The balls can still be moved easily by hand in their mountings.
If a ball has come loose in its mounting, a secure fit can be achieved
again by tapping the sides of the mounting lightly with a hammer.

19
E) Installation instructions
Check the proper mounting of the cam roller on the brake shoes.
The cam roller must not jam in the mounting. It must turn easily, but
without radial clearance.
Replace the cam roller if the journal is severely worn.
When installing new cam rollers, a secure mounting in the brake shoe
can be achieved by pressing in the two side faces in a vice.
Apply copper paste to the brake shoes, to the ball surface and to the
two journals of the cam roller.
See chapter “Maintenance instructions” for recommended media.
Apply copper paste to the two
balls in the brake carrier.
See chapter
“Maintenance instructions”
for recommended media.
Hook a new return spring into the tabs of the brake shoes.
Position the upper brake shoe on the ball pivot point and the cam
roller surface.
Suspend the spring clip on the upper brake shoe.
Tilt the lower brake shoe towards the cover plate until the correct
seating on the cam and on the ball pivot point is achieved; if
necessary, turn the camshaft into the required position. Insert the
spring clip into the groove on the lower brake shoe and hook into
the retainer on the upper brake shoe using a screwdriver.
Ensure that the spring clip is
fitted securely.
Check the assembly and the
proper operational condition
of the installed brakes.
Turn the camshaft by actuating
the slack adjuster by hand and
check the correct positioning
and smooth return of the
brake shoes; readjust the
camshaft bearing, if necessary.

20
E) Installation instructions
Turning down the brake linings
Even after a brake lining replacement with new brake linings, the
brake lining must be in full contact with the braking surface of the
brake drum over its whole surface in order to achieve an optimum
braking effect.
For a uniform contact pattern, the brake lining must therefore be
turned down centrally to the stub shaft on a normal workshop brake
lining lathe.
Set the lathe tool to the diameter of the brake drum + 0.3 mm.
Use the clamping device for the brake shoes,
SAF Part No. 3 349 1001 00.
Leave the clamping device loose at this stage – do not clamp!
Turn the camshaft by actuating the slack adjuster until the brake
shoes are spread sufficiently that the lathe tool can take off material
over the whole circumference of the brake linings.
Now tighten the clamping device.
Turn down the brake linings.
Inspect the brake lining surface all over for complete machining. If
necessary, loosen the clamping device and spread the brake shoes
slightly further and repeat the machining process.
Remove the clamping device.
Remove all chips of the brake lining from the brake shoes and stub
axle.
Brake lining lathe
90 mm diameter supporting tube inner wheel bearing
65 mm diameter supporting tube outer wheel bearing
Order adapter sleeves from the lathe manufacturer.
Installing the wheel hub with brake drum
Completely coat the ABS sensor with copper paste and press into
the sensor holder up to the collar.
Completely coat the wheel bearing seats on the stub shaft and in
the wheel hub with SAF fitting paste (SAF Part No 4 387 0015 06).
See chapter “Maintenance instructions” for recommended media.