Johnson 40-6926 User manual

©2011 Johnson Level & Tool - Rev. 1 1
Automatic Levels
Model No. 40-6926, 40-6960, 40-6962
Instruction Manual
Congratulations on your choice of this Automatic Level. We
suggest you read this instruction manual thoroughly before using
the instrument. Save this instruction manual for future use.
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2©2011 Johnson Level & Tool - Rev. 1
Table of Contents
1. it Contents
2. Features and Functions
3. Location of Parts/Components
4. Operating Instructions
5. Calibration
6. Technical Specifications
7. Care and Handling
8. Product Warranty
9. Product Registration
10. Accessories
1. Kit Contents
Description for Model 40-6926 ty.
26X Automatic Level 1
Instruction Manual with Warranty Card 1
Hard Shell Carrying Case 1
Description for Model 40-6960 ty.
30X Automatic Level 1
Instruction Manual with Warranty Card 1
Hard Shell Carrying Case 1
Description for Model 40-6962 ty.
32X Automatic Level 1
Instruction Manual with Warranty Card 1
Hard Shell Carrying Case 1
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2. Features and Functions
• Water resistant, sealed construction for use in most weather
conditions
• Wire-hung, magnetically dampened compensator
• Large, easy-to-use focusing knob
• 360º horizontal circle
• Penta prism for bubble viewing
• Top-mounted optical sight for quick reference
• Fine adjustment knobs on left and right sides with endless
horizontal drive
• 1:100 stadia for distance estimation
• 5/8” x 11 threads to fit standard tripods
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3. Location of Part/Components
Circular bubble vial
observation prism
Circular bubble vial
Adjusting screws for
circular bubble vial
Eyepiece cover
Eyepiece
focusing knob
Horizontal circle
Leveling screw
Horizontal circle
reference mark
Compensator
check button
Optical sight
Base plate
Focusing knob
Objective lens
Horizontal tangent knob
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4. Operating Instructions
IMPORTANT: It is the responsibility of the user to verify the
calibration of the instrument before each use.
Set-Up
Set the tripod up level and in a comfortable position to view through
the telescope. Connect the instrument to the tripod with the 5/8”-11
central screw. Using the leveling screws, center the circular bubble.
Aiming and Focusing
Focus the cross hairs by turning the eyepiece focusing knob until the
cross hairs are sharp and black.
Focus the telescope by locating a target, such as a leveling rod, using
the optical sight. Looking through the eyepiece, use the focusing
knob to bring the target into sharp focus. Center the cross hair
to the target using the horizontal tangent knobs on either side of
the instrument.
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6©2011 Johnson Level & Tool - Rev. 1
Reading measurements using a Leveling Rod
Height reading
Read the rod where it is intersected by the
horizontal hair. For example, the height reading
in Figure 1 is 2.0 ft.
Distance Measurement
Read the rod where it is intersected by the
upper and lower stadia hairs. In Figure 1, these readings are at 1.9
ft. and 2.1 ft. The stadia ration is 1:100, therefore the distance from
the instrument to the rod is: (2.1-1.9) x 100 = 20ft.
Angle Measurement
As shown in figure 2, sight point A and note the reading on the
horizontal circle. Rotate the level and sight point B. The angle turned
is the difference between A and B. The angle A0B = xº = A - B.
Fig. 1
Fig. 2
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5. Calibration
5.1 Compensator Check Button
Check the compensator for proper operation before use or anytime
the operation of the instrument is in question. Push and release the
compensator check button to shake the compensator. The compen-
sator should return to the exact horizontal position sighted before the
check button was pressed.
5.2 Circular Bubble Vial
Center the vial bubble using the leveling screws, then rotate the
instrument 180º. The bubble should remain centered (Fig. 3). If the
bubble moved from the center, the vial needs adjustment (Fig. 4).
Turn the leveling screws to bring the bubble halfway to center (Fig. 5).
Using the allen wrench, turn the two vial adjustment screws to center
the bubble (Fig. 6).
Repeat the above procedure until the bubble remain centered when
the level is rotated 180º.
Fig. 3 Fig. 4
Fig. 5 Fig. 6
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8©2011 Johnson Level & Tool - Rev. 1
5.3 Line-of-Sight
The line-of-sight needs to be horizontal within 3mm of level to be accurate.
Set up and level the instrument on a tripod midway between two
leveling rods set approximately 100 ft. to 160 ft. (30m to 50m) apart.
Sight rods A and B; the height readings are a1 and b1 (Fig. 7). The
value “H” is equal to (a1 - b1). Move the instrument to within 6 ft. (2m)
of rod A and re-level. Again sight rods A and B; these height readings
are a2 and b2 (Fig. 8).
If a1 - b1 = a2 - b2 = H, the line-of sight is horizontal. If not, the level
should be adjusted as follows.
Because the instrument is set halfway between A and B, any error in the
line-of-sight causes both readings to be erroneous by the same amount.
Error e cancels out, so the value a1 - b1 = H is correct. Therefore,
a2 - H = b3, the adjusting value.
To adjust, unscrew the eyepiece cover.
Turn the adjusting screw with the
adjusting pin (Fig. 9) until the horizontal
cross hair gives the reading b3 on rod B.
Repeat the above procedure until
{(a1 - b1) - (a2 - b2)} ≤ 3mm.
Fig. 7 Fig. 8
Fig. 9
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6. Technical Specifications
Telescope Erect
Magnification 26X (40-6926), 30X (40-6960),
32X (40-6962)
Leveling accuracy ± 1/16"/200 ft. (±1.5mm/160m)
Working range Up to 350’ (100m) (40-6926)
Up to 400’ (120m) (40-6960)
Up to 450’ (130m) (40-6962)
Clear objective aperture 40 mm
Field of view 1º 30’
Shortest focusing distance 0.0315” (0.8m)
Stadia ratio 100
Stadia addition 0
Water resistant Yes
Sensitivity of bubble 8’ (2mm)
Circle graduation 1º
Standard deviation for
1km double-run leveling 0.0689” (1.75mm)
Compensator:
Working range ± 15’
Setting accuracy ± 0.8”
Dimensions 7.520” x 5.197” x 5.394”
(191 x 132 x 137mm)
Weight 3.395 lbs (1.54 g)
Center screw thread 5/8” - 11
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7. Care and Handling
Care must be taken to maintain the accuracy of the instrument.
•After each use, the instrument should be wiped clean and kept in
its carrying case.
• Remove dust from the lenses with a soft brush or a nonabrasive
wipe. Never touch the lenses with your fingers.
• Store the instrument in a dust-free area with low humidity.
• A bag of silica gel dryer is included with each instrument.
8. Product Warranty
Johnson Level & Tool offers a three year limited warranty on each of its
products. You can obtain a copy of the limited warranty for a
Johnson Level & Tool product by contacting Johnson Level & Tool's
Customer Service Department, as provided below, or by visiting our
web site at www.johnsonlevel.com. The limited warranty for each
product contains various limitations and exclusions.
Do not return this product to the store/retailer or place of purchase.
Non-warranty repairs and course calibration must be done by an
authorized Johnson®service center or Johnson Level & Tool's limited
warranty, if applicable, will be void and there will be NO WARRANTY.
Contact one of our service centers for all non-warranty repairs. A
list of service centers can be found on our web site at
www.johnsonlevel.com or by calling our Customer Service
Department. Contact our Customer Service Department for Return
Material Authorization (RMA) for warranty repairs (manufacturing
defects only). Proof of purchase is required.
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