Safe and reliable brakingThe brakes of heavy commercial vehicles
have to endure severe duties. Not only in long or steep descents
and on winding secondary roads, but also in dense traffic. In these
conditions additional retarder systems are essential to secure safe
and reliable braking and to reduce wear of the brake pads.
For these purposes the retarder functions are fully integrated
in the service brake operation. Two different retarder systems are
available:• the primary retarder, MX Engine Brake with exhaust
brake, is
integrated in the engine and most effective at higher engine
speeds
• the secondary retarder, ZF Intarder, is integrated in the
gearbox and very effective at vehicle speeds over 50 km/h
Torque controlIn the torque control mode three different braking
torque levels may be selected with the right-hand steering column
handle.
MX Engine BrakeThe MX Engine Brake is a hydraulically operated
compression brake combined with a butterfly valve in the exhaust
system. The brake power is independent of the engine temperature,
and amounts to max. 340 kW with engine MX-11 and max. 360 kW with
engine MX-13.
ZF IntarderThe ZF Intarder is a hydrodynamic retarder. The
maximum brake power is 500 kW, if not reduced due to high engine
temperatures.
Recommended retarder choiceThere is no strict formula for the
preferred type of retarder. Apart from performance, there are
factors like operating conditions, route characteristics, added
weight, control comfort, fuel efficiency and purchase price that
play a role. Some general guidelines can be based on the specific
qualities of the two retarder systems.
DAF | 1
Retarder SystemsIncreased safety - increased service brake
life
ZF Intarder - TraXon
Bra
king
pow
er
Bra
king
torq
ue
1000
600
500
400
300
200
100
0
1500
0
500
2000
2500
3000
4000
700 3500
4500 NmkW
900
1100
20 40 60 80 100 120 140Vehicle speed (km/h)
0
Braking powerBraking torque
Bra
king
pow
er
Bra
king
torq
ue
500
300
250
200
150
100
50
0
750
0
250
1000
1250
1500
2000
350 1750
NmkW 400
12 15 18 2421Engine speed (rpm)
9
MX-13 Engine Brake
Braking power all ratingsBraking torque all ratings
x 100
A PACCAR COMPANY DRIVEN BY QUALITY
The MX Engine Brake is the best choice for most applications. It
performs independent of vehicle speed and engine temperature, adds
only 15 kg of weight and has no impact on the fuel consumption.
Heavy haulageA combination of MX Engine Brake and ZF Intarder is
recommended for heavy haulage applications. The engine brake is
essential for low speed descents, while the combination provides
continuous high brake performance in the higher speed range.
The ZF Intarder performs chiefly at higher vehicle speeds.
Therefore its higher price and weight (80 kg) are worth considering
for applications with long, high-speed descents.
Endurance braking may be impeded due to a high engine
temperature. The fuel consumption is slightly affected by viscuous
friction in the oil circuit.
Retarder SystemsIncreased safety - increased service brake
life
