We are often asked how the multi power system on models such as the Massey Ferguson 65, 135, 165 etc. works. What really seems to intrigue people is that the engine breaking system works when in high multi-power, but there is no engine breaking when in low multi-power………
With the multi-power system there is one hydraulic clutch pack and also a ratchet type assembly. When in low multi the hydraulic clutch is dissengaged and the drive goes through a pair of gears into a ratchet clutch which takes the drive to the gearbox. There is no engine breaking in low multi because of the ratchet clutch. When you move the transmission to high multi it locks up the hydraulic clutch and the hydraulic clutch gear drives another gear. Because the drive is now turning faster than through the low-multi ratchet clutch, this now becomes a free-wheeling device. It is for this reason that there is engine breaking in high multi power, but no engine breaking in low multi power.
This is also why if you are in high multi going up a hill and you depress the clutch pedal that whilst in gear no roll-back can occur because of the ratchet clutch. ie. both systems are locked together. The hydraulic multi-power clutch is not torque converter, but is merely a multi-plate hydraulically operated clutch pack. The good thing about this is that there is no loss of power through to the gearbox.
The clutch is a conventional clutch and so is the 3 speed gearbox.
The Vintage Tractor Engineer..