Flowserve Handwheels and Limit Stop - Manual (Page 11)

Flowserve Corporation, Valtek Control Products, Tel. USA 801 489 8611 5-11
PUSH-ONLY LIMIT STOPS
(Linear Actuators Only)
Operation
The push-only limit stop is used to limit valve opening.
To set the limit stop:
1. Loosen the limit stop jam nut (see Figure 6).
2. To lengthen the stroke, screw the limit stop bolt
counter-clockwise from the locking stop hub until
the desired position is reached. To shorten the
stroke, screw the limit stop bolt clockwise into the
locking stop hub until the desired position is reached.
3. Tighten the limit stop jam nut firmly against the
locking stop hub.
Maintenance
For proper maintenance of the limit stop, it is important
to maintain a coat of multi-purpose Iubricant on the limit
stop bolt threads at all times. To do this:
1. Vent air pressure on both sides of piston.
2. Loosen the limit stop jam nut.
3. Extend the limit stop bolt until the entire length of the
threaded portion is exposed.
4. Clean and lubricate the threads.
5. Return the limit stop bolt to desired position.
6. Tighten the limit stop jam nut firmly against the
locking stop hub.
Disassembly
Refer to Figure 6:
WARNING: Repressurize line and actuator to atmo-
spheric pressure before disassembling the hand-
wheel or removing the actuator from the valve, or
serious personal injury could result.
1. The limit stop may be disassembled while mounted
on the valve, or the actuator can be removed and
disassembled separately (see the valve’s mainte-
nance bulletins for instructions).
2. Vent air pressure on both sides of the piston.
Loosen the limit stop jam nut and screw the limit
stop bolt counter-clockwise until it can be removed
from the limit stop hub. Remove the O-ring and jam
nut from the limit stop bolt.
3. Screw the limit stop hub off the cylinder. Larger
sizes are designed with an internal flanged hub. If
this is the case, remove the flange bolts. Remove
the gasket from the limit stop hub.
4. Actuator may now be disassembled according to
Maintenance Bulletin 2.
Reassembly
Refer to Figure 6 and proceed as follows:
1. Make sure all internal parts are thoroughly cleaned
and lubricated before beginning reassembly. Use
only new O-rings and gaskets (O-rings should be
lubricated with a silicone lubricant, such as Dow
Corning 55 M). Reassemble the actuator according
to Maintenance Bulletin 2.
2. Install a new O-ring on the limit stop bolt and a new
gasket on the limit stop hub.
3. Screw the limit stop hub into the cylinder or on larger
sizes, reinstall hub and flange bolts.
4. Make sure the end of the hub seats properly with the
spring button. Tighten the limit stop hub (or flange
bolts) only enough to make an adequate air seal
with the gasket.
5. After installing the jam nut on the limit stop bolt,
screw the limit stop bolt into the limit stop hub until
the desired position is reached.
6. Tighten the jam nut against the limit stop hub.
PULL-ONLY LIMIT STOPS
(Linear Actuators Only)
Operation
WARNING: The limit stop bolt and jam nuts are
moving parts. Keep hands, hair or clothing clear
during operation or serious injury can result.
The pull-only limit stop is used to limit valve closing. To
set the limit stop:
1. Loosen the limit stop jam nuts (see Figure 7).
2. Apply air under the piston until the limit position is
reached.
Figure 6: Push-only Limit stop
NOTE: Item numbers shown above correspond directly to the valve’s
bill of material. Refer to the bill of material for specific part numbers.
O-ring
(Item No. 376)
Spring Button
(Item No. 227)
Cylinder
(Item No. 202)
Jam Nut
(Item No. 350)
Limit Stop Bolt
(Item No. 380)
Limit Stop Hub
(Item No. 391)
Hub Gasket
(Item No. 248)