Can semi-tractor trailer trucks park within City limits?

It shall be unlawful for any person to park a truck, semi-trailer, tractor or truck tractor with a five-ton license certificate or plate and which exceeds 8' in width or 21' in length on any street within the city except for that period of time necessary for loading and unloading, delivery or collection of goods, wares and merchandise, but in no event shall this time period exceed 2 hours.