Table of Contents
Advertisement
3
Introduction
Introduction
Features
Four-Piston Quadraulic™ Disc Brake Caliper
Meritor Quadraulic™ disc brakes have a four-piston, fixed-mount
caliper design for use on both front and rear drive axles. An
installation includes the following major components — the caliper
assembly, torque plate assembly, optional dust shield, hub or rotor
assembly and attaching hardware.
There are three caliper types and they are referenced by the piston
diameter: 70 mm, 64 mm and 64 mm Lite.
NOTE: The 64 mm Lite version is not a replacement equivalent for
the base 64 mm caliper.
The operation and service instructions in this maintenance manual
apply to all three Quadraulic caliper models.
Caliper
Meritor caliper assemblies (Figure 2.1) are designed as follows.
• The caliper assembly consists of two halves assembled with four
bolts and washers.
• It includes four hydraulic piston bores, two brake pads, two
stainless steel lining wear plates installed with button head bolts,
a pad retainer spring and bolt, bleed screw and crossover tube.
• The piston bores contain the pistons, piston seals and piston
boots.
• The crossover tubes connect the two halves of the caliper piston
to supply brake fluid to the outboard pistons.
How to Identify the Caliper
Check for an assembly number on the side of the caliper (Figure 2.1)
for specific handed part numbers.
If a part number is not visible, the calipers can also be identified by
piston diameter size. The two sizes available are: 64 mm or 70 mm.
They are visually identifiable by boot color (64 mm is red, 70 mm is
black).
The 64 mm Lite caliper also has a red boot and is distinguishable
from the base 64 mm caliper by the six M16 size mounting bolts.
Assembly check - The caliper bleed screws should be higher than
the crossover tube when assembled to the torque plate to allow
effective brake bleed.
MM-2075 / Revised 09-23
Page 6
Torque Plate
The torque plate assembly (Figure 2.2) may have a provision for
an anti-lock braking system (ABS) sensor using either a bolt-
on bracket, press-in bushing, clearance hole or slot. It also has
provisions to mount an optional dust shield to protect the rotor
and brake assembly from road contamination. When the ABS is
not used or the sensor is mounted through the axle flange, the
supports are not equipped with the sensor bracket.
Hub and Rotor
Meritor hub and rotor assemblies (Figure 2.2) incorporate the
following design features.
• The hub and rotor assemblies consist of a hub and rotor, fitted
with bearing cups and wheel attachment studs.
• There are two types of rotors used — a U-shaped rotor and a
hat-shaped rotor.
• Some rotors are equipped with a cast-in ABS speed sensor tooth
wheel, typically with 100 slots. Some rotors have separate ABS
speed sensor tooth wheels attached to the rotor with bolts.
• Front hub and rotor assemblies can have various ABS speed
sensor tooth wheels such as a separate ring mounted to the
inboard end of the hub, ABS teeth integral to the rotor, or a
separate ABS ring attached to the rotor by bolts.
• There are various hub configurations offered to accept
the 19.5-inch (495.3 mm) eight-hole wheels, as well as
22.5-inch (571.5 mm) 10-hole wheels with the hub-piloted or
stud-piloted system.
Operation
The Quadraulic brake is a fixed mount caliper - the only part that
moves during a brake application is the piston and related brake
pad.
The caliper receives hydraulic fluid pressure by way of the centrally
located inlet port. The inlet port can accept either a banjo bolt
connection or an inverted flare-type connection.
The arrows in Figure 3.1 show the fluid handling from the inlet port
to each of the pistons. Also shown is the fluid handling for bleeding
air from the caliper. Because there are two bleed screws, a special
bleeding sequence is required to remove all air from the system.
This procedure is detailed in Brake Caliper Bleeding Procedure on
page 19.
Copyright Meritor, Inc., 2023
(16579)
Printed in USA
Advertisement
Chapters
Table of Contents
