Abstract: A sewage collection and disposal system for a passenger transport vehicle comprises a sewage collection tank having a sewage inlet connected to a sewer pipe of the vehicle and a sewage discharge outlet for draining sewage from the sewage collection tank under control of a drain valve. A cleaning liquid supply pipe connects a source of cleaning liquid under pressure to a cleaning liquid supply connection for introducing cleaning liquid into the sewage collection tank. A precharge tank that is in fluid communication with the sewage collection tank is also connected to the cleaning liquid supply pipe, whereby cleaning liquid is supplied to the precharge tank when cleaning liquid is supplied to the cleaning liquid supply member. A blower establishes a partial vacuum in the sewage collection tank when the drain valve is closed, whereby pressure difference between the precharge tank and the sewage collection tank forces cleaning liquid present in the precharge tank into the sewage collection tank.

Abstract: A centrifugal liquid pump includes an impeller and a hub for the impeller, whereby gases entrained in the liquid are separated from the liquid and collect near the hub by centripetal action. A shaft is connected to the hub for rotating the impeller, and a passageway extends axially through the shaft. A gas entry is provided near the hub in communication with the passageway. An air pump is provided at an opposite end of the shaft for evacuating the separated gases collected near the hub. The air pump is independent of and remote from the impeller and is in communication with the passageway extending axially through the shaft.