3 - Description46GearboxThe HF540, HF540D and HF640D blowers have a two-speed gearboxwith neutral position.Upper pos: High speedMiddle pos.: NeutralLower pos.: Low speed€ DANGER! Do not attempt to engage or disengage the speedwith the PTO in operation.HF 640D TurbinesThe centrifugal blower units contain a galvanised steel turbine. Thedifference between the single model and the double model is thatthe double provides the same power as two single turbinescombined.The position of the blades in this type of turbine is fixed. Their anglecannot be changed like in axial fans.The turbines are allowed to turn at a maximum of 540 r.p.m.The clutch is at the centre of the turbines, which ensures smoothstartup and stops - see section “Clutch” for further information.Clutch (All blower types)The clutch is integrated at the centre of all the fan models and willensure a smooth start-up and stop of the fan. The clutch design mayvary from model to model, but the functioning and maintenance isthe same.± WARNING! The clutch is a vital part in the blower unit. Poorcondition could cause the blower unit to break or explode.The condition of this part should be regularly checked. Pleasecarefully read the section on its ‘Maintenance’.€ DANGER! The clutch is one of the most important parts in theblower unit in terms of safety. Make sure that it is in perfectconditions (i.e. that it is not blocked, etc.) Otherwise, it couldcause the blower unit to explode.
