Specifications, Service and Repair of Farm and Lawn Tractors


Massey Ferguson 8240 tractor Powershift Gearbox

The AG150 and AG250 Powershift gearbox comprise forward and rear housings containing seven shafts and nine clutches. Six speed clutches and three range clutches.

Three clutches must be hydraulically engaged in order to transmit engine power.

These MF 8240 transmissions are fitted with their own Gerotor hydraulic pump, filter, pressure regulating valve, lubricating metering valve and nine proportional solenoid valves to engage the clutches.

These transmissions use an oil tank that is common to the gearbox and axle assembly. The gearbox is coupled to the engine via a splined coupling shaft situated in the transmission and a damper located on the engine flywheel.

MF 8240 AG150 / AG250 Powershift gearbox have the following characteristics:

- 18 forward speeds
- 6 or 8 reverse speeds
- constant meshing, helicoidal gears
- ball and roller bearings to eliminate all vibration
- common axle / gearbox oil tank
- hydraulically controlled multi-plate clutches
- electro-hydraulic gear changes
- 100% modulated gear changes
- adaptation to speed of movement
- reverse shuttle
- compact design in a 2-part housing
- housing also acts as the tractor chassis between the engine and rear axle unit
- pressure lubrication of all clutches
- self-controlled hydraulic pump
- vibration damper in the engine flywheel
- electronically protected.

Massey Ferguson 8240 Transmission

Overall view

(1) Forward transmission housing (2) Rear transmission housing (3) Location of the first stage shaft (4) Location of the second stage shaft (5) Location of the third stage shaft (6) Location of the fourth stage shaft (7) Location of the fifth stage shaft (8) Location of the sixth stage shaft (9) Location of the seventh stage shaft (10) Input shaft and seal (11) 260 psi (18 bar) pressure regulating valve (12) Clutch 2 proportional solenoid valve

Front view

(13) Clutch A proportional solenoid valve (14) Clutch R proportional solenoid valve (15) Clutch B proportional solenoid valve (16) Clutch 1 proportional solenoid valve (17) Clutch C proportional solenoid valve (18) Clutch L proportional solenoid valve (19) (AG 150) clutch M proportional solenoid valve (AG 250) clutch H proportional
solenoid valve (20) (AG 150) clutch H proportional solenoid valve (AG 250) clutch M proportional solenoid valve

Top view

(21) 130 psi (9 bar) pump pressure switch (22) Engine speed sensor (23) Forward speed sensor (24) Calibration sensor (25) Temperature sensor (26) Clutch hydraulic test port - 7/16” plugs (27) Lubricating pressure test port - 9/16” plugs (28) Pump hydraulic test ports - wide plugs (29) IN port (inlet) of the pump from the tank (30) Free return to housing port (31) Pump pressure outlet port (32) Pump pressure inlet port to forward housing (33) Oil outlet port towards oil cooler and lubricating relief-valve (34) Return port for oil from oil cooler (35) Gearbox serial and model number identification plate.

Diagramm showing the meshing of AG-150 pinions

The engine power is transmitted to the 1st stage shaft that drives the shafts of the 2nd, 3rd and 4th stages.

The 1st stage shaft also drives the Gerotor hydraulic pump for the gearbox and acts as the PTO input shaft.

The shafts of the 2nd and 4th stages act as forward speeds with the various ratios of input speed, while the shaft of the 3rd stage acts as reverse with a single input speed ratio.

Diagramm showing the meshing of AG 250 pinions

This allows to obtain forward and reverse speeds. When clutch 1, 2 or R is engaged, it locks the clutch housing to the corresponding shaft.

Each clutch housing is fitted with a pinion that meshes with the other shafts (all having the same ratio), permitting the power to enter via a clutch (1, 2 or R) and to exit via another clutch (A, B or C) and another shaft.

Massey Ferguson 8240 Power transmission route

The various clutches supply six forward ratios and three reverse ratios to the transmission, in accordance with the input clutches (1, 2 or R) or output clutches (A, B or C) selected.

The output from speed clutches directs the power to the clutch of the selected range (L, M or H), thus providing 18 forward speeds and 8 reverse speeds.

In the North American market, the electronic control does not permit the engaging of the two highest speeds. Other international markets may authorise these reverse speeds in relation to the legislation in force in their countries.

Vibration damper and coupling shafts

Tightening torque - M10 bolt (43): 68 – 92 Nm.

AG 150/AG 250 Transmission

(36) Engine flywheel (37) LUK damper (38) Bearing (39) Coupling shaft (40) Spring (41) Input shaft seal (42) 1st stage shaft (43) Bolt