On-need AWD programs push the secondary axle via an active or passive coupling unit or "by an independently driven travel system". The conventional notes that in some cases, the secondary generate program may also provide the main vehicle propulsion. An illustration is a hybrid AWD vehicle in which the primary https://groupak.gr/%CE%B1%CE%BE%CE%B5%CF%83%CE%BF%CF%85%CE%AC%CF%81-4%CF%874