Introducing the Actuator

ALGA actuators were engineered and manufactured to provide maximum torque

output with minimum supply pressure. ALGA actuators are suitable for the operation

of any quarter-turn operation like ball, plug, butterfly valves or dampers, in both

on/off and modulating heavy-duty service.

The actuator (Figure 4) is made up of a weatherproof scotch yoke mechanism

transforming the linear movement of the pneumatic cylinder (on closing or opening)

into the rotary movement, which is necessary for operation. The angular stroke of

the yoke is adjustable between 82° and 98° by means of the external mechanical

stops screwed into the left wall of the mechanism housing and into the end flange

of the pneumatic cylinder. The cover of the scotch yoke mechanism is arranged

for the assembly of the required accessories (positioner, signaling limit switches,

position transducer, etc.) by means of proper matching units. The above-mentioned

accessories are operated by the actuator drive sleeve. The housing of the scotch yoke

mechanism has a flange with threaded holes to fix the actuator to the valve either

directly or, if required, with the interposition of an adaptor flange or a mounting

bracket. The actuator yoke has a hole with keyways suitable for the assembly of an

insert bush the internal hole of which is machined (by Biffi or at customer’s care),

according to the shape and dimensions of the valve stem. Biffi can supply different

types of control system following  the customer’s requirements.