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RP-95028B/N page 2 of 2

Mounting 

1. 

Mount the RP75 using a mounting bracket as illustrated in

Figure 1

(see page 1 of this bulletin for mounting hole dimen-

sions.). If installing the RP75 to an engine com-
partment firewall, go to Step 2. 

2. 

If installing the RP75 to an engine
compartment firewall, drill a 37/64
in. (15 mm) diameter hole in the
firewall (see 

Figure 2

).

3. 

Remove the 

reset knob

on the RP75 by loosening the 

allenhead

screw

on the knob. 

4. 

Remove the 

mounting nut

and insert the RP75 

reset stem

through the hole from the back of the firewall. 

5. 

Replace the mounting nut and tighten. Reinstall the reset knob.

Typical Wiring Diagrams

Wire the RP75 appropriately (see 

Figure 3

). 

NOTE: 

RP75 is voltage

rated; do not apply 24 VDC to 12 VDC model and vice versa. Also,
the 117PH Magnetic Switch is rated for both 12 and 24 VDC circuits
but voltage must be specified when ordering the 518PH or 761APH
Magnetic Switches.

Installing Cable or Chain

1. 

To install the control linkage (cable or chain), apply voltage to
the RP75. Push in the reset knob. If installing the cable, insert
the 

cable attaching nut

into the RP75 and tighten snugly (see

Figure 1

). 

DO NOT OVERTIGHTEN 

or threads may strip.

Attach and tighten outer cable securing nut. If installing the
chain, attach the “S” hook to the RP75 (see 

Figure 1

). 

2. 

Attach the other end of the cable or chain to the injection pump
or air intake shut-off lever so it moves freely without sharp
bends and without binding.

Operation Test

NOTE: 

Some method must be provided to disconnect (lockout) all

normally closed SWICHGAGE

®

circuits when starting (such as

through the appropriate Magnetic Switch). 

1. 

Reset magnetic switch.

2. 

Push in RP75 reset stem until coil latches the trip mechanism.

3. 

Start engine and observe that all locked out contacts clear.

4. 

With engine running, ground SWICHGAGE

®

contact. The

Magnetic Switch will trip thus removing voltage to RP75. The
engine should shutdown immediately. If the engine does shut-
down, adjust control linkage (cable or chain) to ensure that shut-
off lever travels the full length in both directions. 

RP75

Magnetic Switch Energized to Run

SWICHGAGE® 

C

S

B

Battery

117PH

RP75

Magnetic Switch Energized to Run

SWICHGAGE® 

G

B

SW1 SW2

N.C.

Battery

518PH

RP75

Time Delay On Start

SWICHGAGE® 

G

B

S

N.O. N.C.

Battery

761APH

Installation Instructions

WA R N I N G

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.

Mounting
Bracket

Lockwashers
(4 required)

1/4-20 Nut
(4 required)

Wiring 
Terminals

Cable 
Attaching Nut 

Outer Cable
Securing Nut

“S” Hook

Chain

Reset Knob
and Stem

Push to Latch

Firewall

Reset

Knob

Mounting

Nut

Reset

Stem

Allenhead

Screw

Figure 1

Figure 2

Figure 3

CAUTION

:

Shut-off lever should not pull hard

against the stop in the “off” position.

WARNING

:

The

firewall must be capa-
ble of withstanding the

push and pull force of the RP75.

CONTROL SYSTEMS & SERVICES DIVISION

P.O. Box 1819
Rosenberg, Texas 77471 USA
Phone: +1 281 633 4500  Fax: +1 281 633 4588
E-mail: [email protected]

FRANK W. MURPHY, LTD

Church Rd Laverstock
Salisbury SP1 1QZ UK
Phone: +44 172 241 0055  Fax: +44 172 241 0088
E-mail: [email protected]
Web site: www.fwmurphy.co.uk

COMPUTRONIC CONTROLS, LTD

41 - 43 Railway Terrace Nechells
Birmingham B7 5NG UK
Phone: +44 121 327 8500  Fax: +44 121 327 8501
E-mail: [email protected]
Web site: www.computroniccontrols.com

FW MURPHY INSTRUMENTS (HANGZHOU) CO. LTD 

77 23rd Street
Hangzhou Economic & Technological Development Area
Hangzhou, Zhejiang 310018 China
Phone: +86 571 8788 6060  Fax: +86 571 8684 8878

FW MURPHY

P.O. Box 470248
Tulsa, Oklahoma 74147 USA 
+1 918 317 4100  Fax: +1 918 317 4266 
E-mail: [email protected]

INDUSTRIAL PANEL DIVISION

Fax: +1 918 317 4124
E-mail: [email protected]

MURPHY POWER IGNITION

Web site: www.murphy-pi.com 

w w w .

fwmurphy

. c o m

Printed in U.S.A.

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