Abstract: Mechanically pressurized dispensing systems are disclosed that are manually charged by the user and that dispense substances from a pressurized dispenser as an aerosol. The dispensing system comprises in various embodiments mechanical pressurization assemblies, and particularly an actuator assembly and a collar cap assembly. Preferred embodiments incorporate a spindle and a piston to mechanically charge the dispensing system when an actuator housing of the actuator assembly is manually rotated. Other dispenser systems are disclosed providing a threaded piston utilized in the mechanical charging of the dispensing system. Methods of pressurizing dispensing systems and other methods are also disclosed.