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Model MTH6 Tach/Hourmeter Overspeed Switch
Installation and Operation Instructions
MTH-96116N
Revised 04-05
Section 20
(00-02-0778)
Description
Microprocessor-based digital tachometer and hourmeter with a built-in
overspeed switch. This Murphy instrument is highly accurate and depend-
able. It measures speed and running hours and can give an alarm or shut
down the engine on overspeed.
RPM data for the tachometer and overspeed switch is supplied by a mag-
netic pickup or a battery charging alternator equipped with a “Tach” termi-
nal (auxiliary AC terminal). The magnetic pickup is installed into the fly-
wheel housing of an internal combustion engine, so that the starter ring gear
acts upon it to generate a voltage pulse each time a gear tooth passes the end
of the magnetic pickup.
Specifications
Power Requirements: 8-40 VDC (12, 24 or 32 VDC system).
Maximum Current:
12 VDC: 0.011 A, backlight Off; 0.025 A, backlight On.
24 VDC: 0.008 A, backlight Off; 0. 015 A, backlight On.
32 VDC: 0.007 A, backlight Off; 0. 010 A, backlight On.
Operating Temperature: -4° to 158°F (-20° to 70°C).
Storage Temperature: -40° to 185°F (-40° to 85°C).
Case: 1018 Polycarbonate/Polyester blend.
Speed Input: 4.5 Vrms minimum.
Input Frequency Range: 25 Hz to 20 kHz.
Overspeed Switch Rating: 2 A, 50 VDC.
Overspeed Range: 0 to 9000 kHz.
Pulses per Revolution: 4 to 255.
Tachometer Range: 0 to 65,535 RPM.
Tachometer Accuracy: ±1% of display reading,
or -2 RPM whichever is greater.
Hourmeter Range: 0 to 99999 hrs.
Hourmeter Resolution: ±0.1 hour to 9999.9; ±1 hour 10,000 and up.
Reset Hourmeter: Ground terminal #5 to reset hours to zero.
Shipping Weight: 14 oz. (435 g).
Shipping Dimensions: 5-1/2 x 5-1/2 x 5-1/2 in. (140 x 140 x 140 mm).
MTH6 Mounting Schematic
To mount the MTH6 to your panel, a 3-3/8 in. (86 mm) diameter mount-
ing hole is required. Remove the mounting bracket and lock nuts (provid-
ed with the unit).
Insert the MTH6 module from the front of the panel, see schematic below.
Replace mounting bracket and secure in place with the lock nuts.
Please read the following information before installing. A visual inspection of this product for damage during shipping is recommended
before mounting. It is your responsibility to have a qualified person install this unit.
GENERAL INFORMATION
WARNING
BEFORE BEGINNING INSTALLATION OF THIS MURPHY PRODUCT
✔✔
Disconnect all electrical power to the machine.
✔✔
Make sure the machine cannot operate during installation.
✔✔
Follow all safety warnings of the machine manufacturer.
✔✔
Read and follow all installation instructions.
Dimensions
3-1/8 in.
(79 mm)
15/32 in.
(12 mm)
3-33/64 in.
(89 mm)
Diameter
3-5/8 in.
(92 mm)
Diameter
5
6
7
8
9
4
3
2
1
3-9/16 in.
(90 mm)
3-3/8 in.
(86 mm) Dia.
®
FRANK W.
MTH6
MFR.
®
FRANK W.
MFR.
ENTER
SETPOINT
Mounting
Bracket
®
F
R
A
N
K
W
.
MTH6
M
F
R
.
E
N
T
E
R
SETPOINT
MTH6 Module
Panel
Mounting Hole
Mounting
Bracket
Nuts to
Secure
Mounting
(provided)
Side View
Front View
Back View
Mounting Hole
MTH-96116N page 1 of 2