Case IH Steiger 370 CVT Service Manual page 49

Front axle system - Powered front axle
315 and 425 series wheeled axle lube external plumbing components
The 4WD tractors use a pressurized lubrication system for the front drive axle (1), the rear drive axle (2) and also for
the optional power take off (PTO) output drop box, (if equipped). Axle lubrication oil is drawn from and returned back
to the hydraulic reservoir. The lubrication pump (5) is a gear pump mounted furthest from the transmission in the
hydraulic pump assembly. The lube pump draws oil from the hydraulic reservoir through a supply tube (6) and also
draws air from the top of the reservoir to cause the pump to deliver aerated lube oil to the axles. Air is introduced to the
lube pump inlet through a separate air line (7) from the top of the reservoir, through a 2 mm (0.079 in) orifice drilled
into the side of the suction tube, near the lube pump. The lube oil is aerated to slightly pressurize the axles to force
the lube oil to return back to reservoir without flooding the axles with oil. Because the lubrication oil system operates
at a very low pressure, 1.7 bar (25 psi), the pump can tolerate the introduction of the air into the inlet. Because
the hydraulic oil is used for the axle lubrication, use the oil specified in the operators manual because of its proven
performance. The lube pump supplies a common aerated oil supply (8) to both axles. Outlet flow from the lube pump
connects to a tee near the front axle and then splits to send a common pressurized lube oil supply to both the front
and rear axles.
Lubrication oil from the lube pump is delivered to a tee (10) on the driveshaft input side of each axle. From the input
oil tee, an external tube (11) carries excess lube oil to a 1.7 bar (25 psi) check valve (12) at the opposite side of the
differential housing, which regulates the lube oil pressure delivered to each axle. This check valve also has a 1.6 mm
(0.063 in) orifice within the poppet to allow some lubrication oil to pass through before it opens. Also from this input
oil tee, oil is delivered into the internal pinion gear mesh, pinion shaft bearings, and park brake. On the front axle (1),
the lube oil is delivered to the pinion bearing through a small external tube (16). Lube oil also then flows through an
internal jumper tube to the brake side planetary and to the differential area. Lube oil that flows through the differential
area then flows to the brakes and ring gear side final drive planetary.
The aerated oil causes a slight buildup of pressure within the axles. The lube oil collects at the bottom of the axle
housings. On the 315 and 425 series axles, the return port (23) is located low on the side at the drive shaft input side
of the axle. With this return port location, the air pressure causes the oil to collect and return from the axle housing.
On the 315 and 425 axles, a standpipe is installed inside the axle housing at the return port. A cross drilled hole
is located in the side of this standpipe is 75.5 mm (2.97 in) below the centerline of the differential. Because of the
standpipe, the 315 and 425 axles operate with more oil within the axle housing. The return oil hose (25) from the rear
axle passes through the articulation joint along with the lube supply oil hose and also other hydraulic plumbing. The
rear axle return hose and the front axle return hose (26) connect to a return manifold pipe near the reservoir which is
then connected to the reservoir.
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