The all-new electric Mercedes-Benz GLC uses a One-Box brake system that merges the brake booster, master cylinder and ESP control components into a single module, with recuperation of up to 300 kW handling most deceleration. Mercedes-Benz USA detailed the system this week in updated U.S. press information for the GLC 400 4MATIC Electric, the 483-hp launch model rated by the company at up to 350 miles of EPA range. According to Mercedes-Benz, the hydraulic wheel brakes are not required in over 99 percent of braking events.
Highlights
- One-Box architecture: booster, master cylinder and ESP control combined in one compact module, replacing previously separate components
- Recuperation: up to 300 kW; the company says everyday deceleration is handled almost exclusively by the electric drive
- Driver control: four recuperation levels (D-, D, D+ and D Auto), with one-pedal driving in D- and brake-pedal recuperation always active
How the One-Box System Blends Regenerative and Friction Braking
For each brake application, the system calculates the maximum available recuperation and the minimum contribution needed from the wheel brakes. Mercedes-Benz says the result is a steady, consistent pedal feel whether a given stop is performed by the electric motors, the hydraulic brakes or a blend of the two. In everyday driving, the company says, deceleration is handled almost exclusively through recuperation, which both extends electric range and limits use of the friction brakes.
The rear drive unit, a permanently excited synchronous motor Mercedes-Benz says it developed in-house, operates through a two-speed transmission; a front drive unit on the 4MATIC model engages via a disconnect unit that couples or decouples almost instantly as conditions change. Both drive units use silicon carbide inverters.
Recuperation Modes and One-Pedal Driving
Drivers select from four settings:
- D-: maximum recuperation, enabling one-pedal driving
- D: standard recuperation
- D+: no recuperation (coasting)
- D Auto: intelligent recuperation adjusted to the driving situation
Recuperation through the brake pedal remains active in every mode.
Chassis and Stability Functions Tied to Braking
The brake system integrates with several other GLC functions. A Terrain drive program on the GLC 400 4MATIC Electric permanently engages the front axle on dirt and gravel and retunes the drivetrain, steering and brakes for the surface. With the optional trailer hitch, ESP trailer stabilization is included alongside Trailer Maneuvering Assist, which steers automatically when reversing at up to 4 mph on grades of up to 15 percent.
Mercedes-Benz’s ESP control logic is one of the three components now packaged inside the One-Box module. Standard PRE-SAFE preventive occupant protection can pre-tension seat belts and close windows ahead of a potential impact, and the optional Agility & Comfort Package adds rear-axle steering of up to 4.5 degrees below 37 mph, which the company says reduces the turning circle by three feet.
The 94-kWh usable battery sits on an 800-volt architecture with DC fast charging Mercedes-Benz rates at up to 330 kW. The electric GLC is assembled at the Bremen plant on the same line as combustion models.
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