If it says Terrot on the tank, then that is what it is! Terrot is a French manufacturer, started making bicycles in 1901 and progressed to motorcycles as did many. They became one of the leading French motorcycle manufacturers producing many 175cc machines. The suspension is 'Plunger' type, the spring is contained within the vertical tube, though this example makes it operate with a 'swinging arm', so it's a combined system.