2022.3-0000010 OM
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Figure 3.10.1 – Transmission hydraulic system circuit diagram (without FPTO)
The hydraulic system is meant to ensure controlling the GB reduction unit, FDA
drive, rear PTO, FPTO (if installed), rear axle DL, clutch hydraulic booster and also lubrica-
tion of transmission bearings, cooling of transmission components and cleaning of trans-
mission oil.
The gear oil pump 1 (figure 3.10.1) with a disengageable drive mechanism is
mounted on the left side of the clutch body.
The pump sucks oil from the transmission case 1 through the mesh suction filter 1 and
supplies it to the system through the safety valve
1, adjusted for the pressure of 1.8…2 MPa,
to the full-flow mesh filter A2 and further to the centrifugal distributing filter A3. Apart from filter-
ing elements a ball valve
2 is mounted in the mesh filter A2 housing, it provides overflow
of the working fluid when the inlet and outlet pressure difference exceeds 0.35MPa.
The cleaned oil is supplied under the pressure of 0.9…1 MPa to electro-hydraulic valves
P, controlling the FDA drive, the rear axle DL and the GB reduction unit, accordingly. The electro-
hydraulic valves are connected by means of oil pipelines with the executive mechanisms: FDA
drive friction clutch
1 for FDA drive on/off; piston
2 for rear axle DL clutch on/off; hydraulic
cylinder for engaging higher or lower passes of the GB reduction unit. Oil is also supplied un-
der pressure to the cock KP controlling the rear PTO and to the clutch hydraulic booster. The
cock directs the flow to the friction clutch
4 or the brake
3. For smooth engagement of the
friction clutch
4 a damping device
is mounted in the hydraulic line.
The oil, cleaned by the centrifugal oil filter A3, is supplied to the lubrication system un-
der the pressure of 0.2…2.5 MPa, maintained by the lubrication valve (lower valve of the dis-
tributing filter
2). Further the oil is delivered to bearings of the GB shafts, of the planetary
reduction units: rear axle final drives, support of FDA drive sliding fork. The oil, drained
through the lubrication valve and the middle valve of the distributing filter, lubricates the dif-
ferential and the rear axle main drive.
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