Performing a Test M14-13655-EN
6-4
When the crosshead is pneumatically assisted, you can operate the Model 8250 either
manually or automatically. The following sections detail a complete example in both of
these modes. In either case, the crosshead must start at the top position.
WarningWarning
Install the “H” bar to prevent the crosshead from falling before workingInstall the “H” bar to prevent the crosshead from falling before working
within the safety enclosurewithin the safety enclosure
CautionCaution
The shock absorber assemblies must be installed when operating in theThe shock absorber assemblies must be installed when operating in the
pneumatically assisted mode. Refer to adjusting the stop blocks andpneumatically assisted mode. Refer to adjusting the stop blocks and
shock absorbers in chapter shock absorbers in chapter 3 for more information.3 for more information.
Manual Mode
To operate the 8250 Machine in pneumatically driven manual mode:
1.
Attach the desired weight set to the crosshead. Do not accelerate 50 lb. (22.7kg), 75
lb. (34kg) or 100 lb. (45kg) crossheads to velocities above 14.5 ft./s (4.4 m/s).
2.
Set the top control pendent switches to MAN and PNEU. If the pneumatic clamp is
installed, set the clamp ON/OFF switch to ON.
3.
Set the pneumatic assist air pressure using the regulator on the top of the rear motor
enclosure.
4.
Place the specimen in the specimen support fixture.
5.
Using the UP button, raise the crosshead to the top position.
6.
Remove any tools, other foreign objects, and the safety "H" bar from the enclosure
and close the doors. The ARM button illuminates.
7.
Press and hold the ARM button. The audible alarm sounds and the pneumatic clamp
(if installed) closes.
8.
While still holding the ARM button, press the FIRE button. The latch hook opens
allowing the crosshead to fall and strike the specimen.
9.
If a pneumatic clamp is installed, the clamp plate rises when the ARM button is
released. When a ductile specimen has been tested, it must be stripped from the tup.
To strip the specimen, press and hold the CLEAR button on the pendent. After the
center piston of the pneumatic clamp is fully raised, press the ARM button to bring
the clamp plate down and strip the specimen from the tup.
10.
Press the DOWN button to retrieve the crosshead. The latch mechanism stops
automatically and engages the crosshead.
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