Samson 3274 Mounting And Operating Instructions

Also see for 3274: Mounting and operating instructions Mounting and operating instructions Mounting and operating instructions

8 EB 8340 ENDesign and principle of operation3.2 Principle of operationÎ Refer to Fig. 1The pressure-tight actuator housing (1),which also serves as the oil reservoir, con-tains the cylinder housing (2), cylinder (5.1)and piston (5.2), motor (6.1), pump (6.2),and solenoid pilot valves (6.4).The oil pump (6.2) driven by the motor (6.1)feeds compressed oil to the correspondingcylinder chamber over the check valve (6.3)and pilot valve (6.4). The solenoid valves areclosed in the de-energized state and openwhen a controller output signal is applied.When an end position is reached or whenthe thrust is too high due to external forces,the motor is switched off.Depending on the version, the actuatorshave no compression springs or areequipped with one or two compressionsprings (5.7, 5.8). The motor in Types 3274-11, -12, -15, -16 as well as -21 to -23 canonly move the stem in one direction. Thestem is moved by spring force in the otherdirection.Actuators with electric override have twopushbuttons to extend or retract the actuatorstem.The actuators with mechanical override havean additional gear housing. An Allen keymust be inserted to activate the overridefunction. In combination with a release but-ton on the top of the actuator housing, theactuator stem can be extended or retracted.Versions with fail-safe action have aspring-return mechanism and an additionalsafety solenoid valve which opens when thepower supply is interrupted, reducing thepressure on the cylinder chamber. The springassembly moves the valve plug to the fail-safe position. The direction of action (actua-tor stem extends or retracts) depends on howthe springs are arranged in the actuator.Risk of actuator damage through openingthe device.Do not remove the housing cover.3.3 AccessoriesThe actuator can be fitted with a variouscombination of accessories.Table 1: Combination of accessoriesAccessoriesPositioner • •Position transmitter • •Resistance transmitter 1 1) • • • • • • • •Resistance transmitter 2 • • • • • •Mechanical limit contact 1 • •Mechanical limit contact 2 • • • • •Mechanical limit contact 3 • • • • •Inductive limit contact 1 • • • • •Inductive limit contact 2 • • • • •All accessories are housed in the terminalbox (3). To control switching and indicatingcomponents, the travel of the actuator stem,which is picked up at the shaft, is convertedinto a rotary motion by a rack-and-piniongear. Accessories can be retrofitted. Table 1on page 22 shows the maximum amountof accessories that can be fitted.NOTICE!