
Drive
Spoon
F100-OAI-2
F100 BIG GUN®
F100 BIG GUN® OPERATING &
ADJUSTMENT INSTRUCTIONS
Nozzle
The F100 is factory set for
typical operation and each
gun is water tested. Minor
adjustments may be required
to change drive operation.
Secondary
Nozzle or Plug
Lower
Bearing
THE DRIVE SPOON:
Adjust to increase or decrease drive power.
When to Adjust:
1. For low pressure operation.
2. For sloping terrain operation.
NOTE: The factory setting of the drive spoon will produce 80 to 90 arm strokes per minutes
and an approximate rotation through 180° arc in one and a half minutes. Short, choppy arm
strokes usually indicate marginal pressure conditions and necessitate spoon adjustment. The
lower bearing assembly includes a spring loaded disc brake that does not need adjustment.
On sloping terrain, adjust the drive spoon 1/16” into the stream. For traveler operation, sloping
terrain will cause the nozzle pressure to fluctuate 4.3 PSI for every 10 feet of elevation change. A
counter balance kit is available for operation on a tilted riser.
For operation below 40 PSI, adjust the spoon 1/16” into the stream. NOTE: Operation below the
recommended pressure may result in improper mechanical operation, particularly where sloping
terrain conditions exist. For good irrigation droplet conditions, 55 PSI or greater is recommended.
Nelson Irrigation Corp. 848 Airport Rd. Walla Walla, WA 99362-2271 USA Tel: 509.525.7660 Fax: 509.525.7907 E-mail: info@nelsonirrigation.com Web site: www.nelsonirrigation.com

F100 BIG GUN® OPERATING AND ADJUSTMENT
PROBLEM: Drive arm does not swing properly.
SOLUTION: A. Nozzle or barrel partially plugged with debris — unplug.
B. Arm Shaft loose — tighten nut.
C. Bearings dirty or corroded — replace.
D. Insufficient Pressure — 40 PSI minimum for irrigation.
E. Broken or worn drive arm spoon — replace.
PROBLEM: Insufficient water distribution close to the sprinkler.
SOLUTION: Remove secondary plug, install secondary nozzle.
PROBLEM: “Ragged” or turbulent stream discharge.
SOLUTION: A. Debris trapped in nozzle barrel — remove.
B. Inlet riser connection does not allow smooth flow of water into gun — insert
625V (2 1/2”) or 600V (2”) stream straightener vane into 2 1/2” or 2” x 6”
pipe at base of gun.
10/07
C. Nozzle worn excessively or damaged — replace.
PROBLEM: Lower bearing hard to rotate.
SOLUTION: Service lower bearing. (Request SR100 Operation & Maintenance Instructions
for procedure.)
BE CAREFUL!!
1. Read operating instructions before operating sprinkler or making any adjustments.
2. Never make adjustments or perform service while the sprinkler is in operation.
3. Stand clear of an operating sprinkler.
4. Stand clear of the high velocity water stream.
5. Never direct the water stream onto a roadway or electrical transmission lines.
WARRANTY AND DISCLAIMER
Nelson Big Gun sprinklers are warranted for one year from date of original sale to be free of defective materials and workmanship
when used within the working specifications for which the product was designed and under normal use and service. The manufacturer
assumes no responsibility for installation, is limited solely to replacement or repair of defective parts, and the manufacturer will not
be liable for any crops or other consequential damages resulting from any defects or breach of warranty. THIS WARRANTY IS
EXPRESSLY IN LIEU OF ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY
AND FITNESS FOR PARTICULAR PURPOSES AND OF ALL OTHER OBLIGATIONS OR LIABILITIES OF MANUFACTURER. No agent,
employee or representative of the manufacturer has authority to waive, alter or add to the provision of the warranty, nor to make
any representations or warranty not contained herein.
Nelson Irrigation Corp. 848 Airport Rd. Walla Walla, WA 99362-2271 USA Tel: 509.525.7660 Fax: 509.525.7907 E-mail: info@nelsonirrigation.com Web site: www.nelsonirrigation.com