Massey Ferguson 5400 - Issue 1.a
06A01.3
General - GPA20 operation
A . General
The rear axle comprises four main housings:
- the centre housing which contains the bevel gear,
the power take-off gear in all variants and the
4-wheel drive transmission, the handbrake and main
brake control unit. It also supports the two trumpet
housings, the lift cover, and the side covers (see
section 9)
- the right and left trumpets fixed to each side of the
centre housing, and housing the rear wheel drive
axle (see section 6)
- The lift cover fitted to the top of the centre housing
supporting the lift arms which are attached to the
tractor linkage (see section 6).
B . Centre housing assembly
Differential
The drive pinion is driven by the gearbox output shaft,
integral via splined sleeves with the link shaft. The
helical bevel gear assembly transmits the drive to the
trumpet final drive units. A differential lock system
fitted with a coupler and activated by hydraulic pres-
sure is incorporated into the unit (see section 6).
The differential lock controlled either by the Autotronic
5 for models fitted with a power shuttle, or by an elec-
tric circuit for models fitted with a mechanical reverse
shuttle.
4-wheel drive clutch
A driving pinion integral with the drive pinion drives the
counterdriven pinion of the 4 WD clutch assembly.
Drive is then transmitted via Belleville washers to the
clutch output shaft (see section 8).
The 4WD clutch is hydraulically activated.
There is therefore no possibility of accidental disen-
gagement of the 4WD clutch in the event of hydraulic
failure.
Power take-off driveline
The rotation of the shaft passing through the gearbox,
proportional to engine speed, is transmitted to the
hydraulic clutch located at the front of the centre
housing (see section 7).
In the engaged position, drive is transmitted by a
layshaft and a set of driving and driven pinions to the
540 or 1000 rpm PTO shaft. Speeds are selected by a
system of interchangeable shafts (see section 7) or by
coupler (see section 7).
A hydraulic braking device stops the rotation of the
PTO shaft in the disengaged position.
Two additional options are offered:
- 4 speed LSPTO (see section 7)
- GSPTO (see section 7).
Handbrake assembly
A brake assembly comprising three discs and an
expander mechanism is fitted to the drive pinion (see
section 6).
Main brakes
Two pistons fitted laterally in two cavities in the centre
housing act on two discs integral with the trumpet
input sun gears. The brake pistons are activated
hydraulically (see section 6).
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