A2.4 Living Vans A living van' is "a vehicle, whether mechanically propelled or not, which is used for living accommodation by one or more persons and which is also used for the carriage of goods or burden which are not needed by such one or more persons for the purpose of their residence in the vehicle. Living vans are classed as goods vehicles and, depending on their weight, are therefore in either class 4 or 7 within the MOT Service or are subject to HGV plating and testing. A2.5 Play buses A play bus is a motor vehicle which was originally constructed to carry more than 12 passengers but which has been adapted primarily for the carriage of playthings for children. A2.6 Ambulance An ambulance is a motor vehicle which is specially designed and constructed (and not merely adapted) for carrying, as equipment permanently fixed to the vehicle, equipment used for medical, dental, or other health purposes and is used primarily for the carriage of persons suffering from illness, injury or disability. A2.7 Tricycles A motor tricycle is a three wheeled vehicle with wheels symmetrically arranged, a maximum speed over 45 km/h, or engine size over 50 cc.