Vacuum Compatible Versions - Newport 850G Series User Manual

3.5

Vacuum Compatible Versions

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Actuators with gearhead ratios greater than 485:1 are more
susceptible to damage when crashed into a hard stop. For high
gearhead ratios, the motor's momentum appears to be extremely
high when moving at full speed. The mechanical limit switches will
prevent a crash due to over-travel, but will not prevent the actuator
from hitting a hard stop within the travel range (the end of run on
a translation stage or mirror mount for example). Be sure to adjust
the travel limits (Section 3.1) such that the limit switches are
activated before the actuator reaches the end of stage travel. A slip
clutch has been implemented in the drive train to minimize the
probability of damage if a hard stop is encountered, but special
care should be taken to avoid crashing the actuator.
Standard speed 850G actuators can be ordered to operate cleanly within a
vacuum environment. The following describes the alterations that make
the standard actuators vacuum compatible.
The high vacuum model of the 850G Series Linear Actuator, model 850GV6,
incorporates the following features:
1. Six foot Teflon-coated cable from actuator attached to six foot
standard cable.
2. Unanodized aluminum body without label.
3. No fastener sealing compound.
4. The window material is removed.
5. Special lubricant with vapor pressure of 10
6. Vented motor/gearhead/encoder cavities.
7. No scale on the cover and body.
14
CAUTION
-6 Torr at 39°C.