Tank

The oil reservoir for the hydraulic front-wheel drive stores hydraulic oil, accommodates changes in volume and supports deaeration and heat dissipation. A damaged tank or disrupted oil supply can cause pump noise, overheating and loss of auxiliary traction. Within the truck parts range, this subcategory is specifically for vehicles equipped with this type of drive; this reservoir is not a universal hydraulic tank.

MAN HydroDrive and Mercedes HAD (Hydraulic Auxiliary Drive) are different systems with their own reservoirs, connections and maintenance requirements. Applications include suitably equipped MAN TGS and Mercedes Arocs models. Always identify parts using the chassis number and the recorded system specification. Visual comparison or selection based solely on the model name is never sufficient. An engine family, such as MAN D26 or Mercedes OM 471, does not determine which tank fits either.

Check the nominal tank capacity, usable fill volume, expansion space, mounting points and the position of suction, return and any case drain connections. Distinguish versions with integrated filter housings or sensor ports from tanks with external filtration. Internal baffles and the return inlet limit turbulence and air entrainment; a different internal design may therefore make a tank unsuitable even if its external dimensions match.

The material type, corrosion protection and seal material must comply with the original specification and be compatible with the specified hydraulic oil. Also check connection threads, sealing surfaces and the fit of sensor ports. Reservoir pressure is not the same as the pressure on the high-pressure side of the drive system: use only the specified tank pressure and test method, never the operating pressure of the drive circuit.

Common problems include leaking connections, hardened seals, damaged mountings and cracks caused by vibration. On metal reservoirs, pay particular attention to corrosion beneath the retaining straps. A blocked tank breather can disrupt the oil supply. Foaming may indicate air entrainment, an incorrect fluid level or unsuitable hydraulic oil; replacing the tank alone will not necessarily resolve this.

1. Make the system safe. Switch off the auxiliary drive, secure the vehicle against movement and follow the specified cooling and depressurisation procedure before opening any connections.
2. Check the level and inspect for leaks. Measure the oil level on level ground at the specified oil temperature and with the system in the specified state. Clean the exterior and inspect seams, drain plugs, pipe connections and tank supports for fresh signs of leakage.
3. Check the suction side and tank venting. Measure the suction vacuum with a suitable vacuum gauge at the specified test point. Check the tank breather and suction lines; compare readings against the manufacturer's limits.
4. Assess temperature and contamination. Compare sensor readings with a contact temperature measurement. Take a representative oil sample to test for water and particles. Where fitted, check the filter clogging indicator or the differential pressure across the filter.

Replace reservoirs with cracks, severe corrosion or deformed connection faces. At the same time, check retaining straps, rubber isolators and pipe supports: installation under mechanical stress often causes recurring leaks. Only have structural repairs carried out if the manufacturer provides an approved procedure.

Keep lines capped and use clean installation tools. Replace the specified seals and filter elements; flush the circuit in accordance with the manufacturer's instructions if contamination has been detected. Fill only with approved hydraulic oil, observe tightening torques and follow the bleeding procedure. After a functional test, recheck the oil level, temperature and leak-tightness. Braem can provide technical support with parts identification using the chassis number.