Mercedes-Benz_Nail_Gun

Objectives

At the end of this presentation, you should be able to:

1.Explain the function of and purpose for SBC

2.Describe the customer interface with SBC

3.List the hydraulic and electronic components used for SBC

4.Describe how the ???normal??? feel of the brake pedal is maintained

5.Explain emergency operation of the SBC braking system

6.Describe ???temperature compensation???

7.Explain ???Deactivation??? and describe when it is necessary to do it

8.???Activate??? the SBC system

9.Locate tools and the proper procedure for bleeding brakes

These technical training materials are current as of the date noted on the materials, and may be revised or updated without notice. Always check for revised or updated information.

To help avoid personal injury to you or others, and to avoid damage to the vehicle on which you are working, you must always ref er to the latest Mercedes -Benz Technical Publication and follow all pertinent instructions when testing, diagnosing or making repair.

Illustrations and descriptions in this training reference are based on preliminary information and may not correspond to the final US version vehicles. Refer to the official introduction manual and WIS

Reproduction by any means or by any information storage and retrieval system or translation in whole or part is not permitted without written authorization from Mercedes -Benz USA, LLC or it's successors.Published by Mercedes -Benz USA, LLCPrinted in U. S.A.

SBC Incorporates these Functions:

ABS (Anti lock Brakes 1984)

+ASR (Automatic Slip Regulation 1991)

+ETS (Electronic Traction System 1995)

+ESP (Electronic Stability Program 1996)

+BAS (Brake Assist System 1998)

Advantages of SBC

???Improves metering of required brake pressure

???each wheel can be precisely controlled

???Improved BAS function

???monitors release of accelerator pedal and application of brake

???maximum pressure available immediately

???pre-filling of system (overcoming play)

???when the BAS function is anticipated, slight pressure is applied

Advantages of SBC

???Electronic Brake Proportioning: EBP

???allows brake proportioning front to back and side to side

???No pedal vibration during ABS operation

???eliminates ???distraction??? to the driver during critical moments

???indicator light in instrument cluster signals traction loss

???Improved driving dynamics: ABS, ASR, and ESP

???faster response to brake request inputs

Advantages of SBC

???Pressure reduction at standstill

???reduces stress on components

???Dry braking function

???wiper input via CAN

???~every 7 to 14 minutes

???brake actuation changes time interval

Driving with SBC - Wake-Up

SBC is functional as soon as it is ???wakened??? by:

???opening a door (via CAN)

???operating the central locking system (via CAN)

???depressing the brake pedal

???turning key to position 1

???operating parking brake

Driving with SBC ??? Pre-Drive Check (PDC)

When SBC performs a PDC after a "wake-up", the following are checked:

Warning! Pressure is applied to brake calipers (~60 bar)

???reservoir pressure (if low, it will be corrected by running the high pressure charge pump in the hydraulic unit)

???pressure sensors

???control valves

???leak tests

???operational checks

Note: self-tests are constantly conducted during driving (~ once every 16

Driving with SBC ??? Delayed Off Function

Time that SBC remains operational after use:

???with vehicle stationary and was locked = 20 seconds

???with vehicle stationary and ignition in ???0???,

brake pedal not operated = 2 minutes

??? with vehicle stationary, ignition in ???0???,

brake pedal operated in delayed off phase and released again = 4 minutes

Brake Operating Unit

The Brake Operating Unit (BOU) consists of the following:

???Brake fluid reservoir (Do not overfill!)

??? SBC pedal value sensor

??? Tandem master cylinder

??? Brake pressure simulator

(Note: no vacuum booster)

Master Cylinder

??? Fluid level sensor

??? Fluid return line

??? Do not overfill

??? Hydraulic lines to SBC

??? Supply hose to SBC

BOU Tandem Master Cylinder

Fluid reservoir

Fill valves

Primary piston

Floating piston

GF42.46-P-4200-03SL

Traction System Hydraulic Unit (A7/3)

Consists of:

??? SBC control module (A7/3n1)

??? High pressure charge pump (A7/3m1)

??? Pressure reservoir

Emergency Operation Circuit

??? Pressure applied directly to front calipers

??? y1 and y2 not energized

??? b1, b3, and b4 pressure sensors may provide information to SBC control module

??? Media separator/Dividing piston 7 and 8 isolate emergency circuit from normal circuit

GF42.46-P3000SL

Pressure Apply - Rear Wheels

???Brake pedal depressed

???B37/1 and b1 report brake application to control module

???y1 and y2 energized

???y10 and y12 intake control valves energized

???Pressure at each rear wheel monitored by b5 and b6

???Balance valve y4 not energized

Brake pedal pressure

Reservoir pressure

GF42.50-P-4000-04S33

GF42.46-P-1000SL

GF42.46-P-4500-02SL

Pressure Apply - Front Wheels

Brake pedal pressure

Reservoir pressure

???y6 and y8 energized

???pressure applied to left and right dividing pistons 7 and 8

???7 and 8 apply pressure to caliper

???pressure at each wheel monitored by b3 and b4

???Balance valve y3 not energized

GF42.50-P-4000-04S GF42.46-P-1000SL

Temperature Compensation

During continuous brake use the fluid in the calipers expand, this:

???creates high pressure

???prevents valves 7 & 8 from moving

To reduce this pressure, y1 and y2 are pulsed

Deactivation

SBC must be deactivated with SDS before any work is performed on the system. This will prevent the pre-drive check from being automatically performed which could cause injury.

Deactivating the system will:

??? empty the pressure reservoir

(a lower pressure with no volume may be retained)

??? prevent the charge pump from operating

???Note: the warning buzzer is deactivated when accessing SBC with the SDS.

Deactivation

SBC must be deactivated PRIOR to:

???working on the hydraulic system

???removing or installing brake pads

???replacing rotors

???replacing the pressure reservoir

???replacing the BOU