Flowserve Limitorque QXM Linear Base - Manual (Page 10)

MXa/QXM Linear Base FCD LMENIM2315-00 – 6/14
10
2.1.4 Assembly or Adjustment of Optional Stop Nut for LB Subassembly
QXM, MX-10 and MX-40 only.
NOTE: This LB stop nut must not be used for electric motorized operation stops. The stop nut is for use of the manual
override operated closed position only.
IF LB UNIT STOP NUT IS USED FOR ACTUATOR ELECTRIC MOTORIZED CLOSED POSITION, ACTUATOR PREMATURE
FAILURE WILL OCCUR.
To assemble or adjust the stop nut, the LB subassembly must be mounted to the valve with the actuator removed.
Customer must decide on the manual override closed position of the LB unit for placement of the stop nut allowing for
coast when unit is in electric motorized operation. See steps 2 and 3 for recommended stop nut position.
Step 1
Mount the LB with thrust base assembly to valve. Using the thrust base nut lugs, rotate the LB unit to the planned
electric motorized operation closed position (Closed position is where the LB shaft on the bellows side is extended away
from the LB base).
NOTE: LB assembly with QXM/MX actuator may be mounted to valve and electric motorized to the closed position.
Once in the closed position, remove the QXM/MX actuator and proceed with stop assembly.
Step 2
Place stop nut (#12) over the top of the LB shaft (#2) and thread the stop nut down until it bottoms out on the thrust
base thrust nut (#3).
Recommended stop nut position:
Once stop nut has been threaded down to the thrust base nut back-stop off of thrust nut 1 millimeter. For a 3 mm pitch
shaft, 1 mm =
1 ⁄
3
turn; 4 mm pitch shaft = 1/4 turn; 8 mm pitch shaft = 1 ⁄
8
turn; and a 10 mm pitch shaft = 1 ⁄
10
turn.
Step 3
Once stop nut has been positioned, stop nut must be drilled and tap to secure stop in place and shaft must be spot
faced for the set screw. The LB1 requires an M6 set screw and the LB2 requires an M8 set screw.
NOTES:
1. The supplied set screw length is intended to be positioned where the tap drill is within one of the two slots on the
shaft. In this orientation and with small shaft spot face, the supplied set screw length will not protrude past the OD
of the stop nut and disturb the shaft threads. See Figures 2.1 or 2.2.
2. Once stop nut is assembled and actuator has been mounted to the LB unit per section 2.1.6, electrically run unit
to open and then back to the closed position. Declutch actuator and using the handwheel, manually open valve.
If valve is hard to unset in manual mode, the stop nut may be jammed and will need to be moved away from the
closed position. If stop needs readjusting, a new tap in the stop nut and shaft spot face will be required.