Lubricating system for internal combustion engines

A lubricating system for an internal combustion engine (2), comprising a lubricant supply container (9) having an inlet port (8) and a suction port (11), a return line (5, 6) connecting said engine (2) to said inlet port (8) of said supply container (9), a first pump (7) in said return line for transporting lubricant from said engine (2) to said supply container (9), a supply line (12, 14) connecting said suction port (11) to said engine (2), a second pump (13) in said supply line (12, 14) for transporting lubricant from said suction port (11) to said engine (2), an accumulator (16), an accumulator line (15) connecting said accumulator (16) to said engine (2) and to said supply line (14) so that under normal operating conditions said second pump (13) keeps lubricant circulating and said accumulator (16) pressurized, a parallel connection comprising a non-return valve (17) for charging said accumulator and a controllable first valve (19) connecting said accumulator (16) to said accumulator line (15), a sensor (S) for sensing a pressure drop signifying an inadequate lubricant supply to said engine under operating conditions other than normal for controlling said controllable valve (19) to open for feeding lubricant from said accumulator (16) to said engine (2) under said other than normal operating conditions, said supply container (9) further comprising at least one venting and air admission port and at least one controllable second valve (24 or 25) in said at least one venting and air admission port for keeping said port open under said normal operating conditions and for closing said port under said other than normal operating conditions, whereby said engine is lubricated even in an upside-down position by said accumulator (16).