Product Manual 36052
(Revision A)
Original Instructions
Magnetic Speed Pickup
for PG, UG-8, and UG-40 Governors
Installation and Operation Manual
This is the safety alert symbol. It is used to alert you to potential personal
injury hazards. Obey all safety messages that follow this symbol to avoid
possible injury or death.
DANGER—Indicates a hazardous situation which, if not avoided, will result in death
or serious injury.
DEFINITIONS WARNING—Indicates a hazardous situation which, if not avoided, could result in
death or serious injury.
CAUTION—Indicates a hazardous situation which, if not avoided, could result in
minor or moderate injury.
NOTICE—Indicates a hazard that could result in property damage only (including
damage to the control).
IMPORTANT—Designates an operating tip or maintenance suggestion.
The engine, turbine, or other type of prime mover should be equipped with an
overspeed shutdown device to protect against runaway or damage to the prime
mover with possible personal injury, loss of life, or property damage.
The overspeed shutdown device must be totally independent of the prime mover
control system. An overtemperature or overpressure shutdown device may also
be needed for safety, as appropriate.
Read this entire manual and all other publications pertaining to the work to be performed before
installing, operating, or servicing this equipment. Practice all plant and safety instructions and
precautions. Failure to follow instructions can cause personal injury and/or property damage.
This publication may have been revised or updated since this copy was produced. To verify that
you have the latest revision, be sure to check the publications page on the Woodward website:
www.woodward.com/publications
The current revision and distribution restriction of all publications are shown in manual 26311.
The latest version of most publications is available on the publications page. If your publication is
not there, please contact your customer service representative to get the latest copy.
Any unauthorized modifications to or use of this equipment outside its specified mechanical,
electrical, or other operating limits may cause personal injury and/or property damage, including
damage to the equipment. Any such unauthorized modifications: (i) constitute "misuse" and/or
"negligence" within the meaning of the product warranty thereby excluding warranty coverage
for any resulting damage, and (ii) invalidate product certifications or listings.
To prevent damage to a control system that uses an alternator or battery-charging
device, make sure the charging device is turned off before disconnecting the battery
from the system.
To prevent damage to electronic components caused by improper handling, read
and observe the precautions in Woodward manual 82715, Guide for Handling and
Protection of Electronic Controls, Printed Circuit Boards, and Modules.
Woodward reserves the right to update any portion of this publication at any time. Information provided by Woodward is
believed to be correct and reliable. However, no responsibility is assumed by Woodward unless otherwise expressly
undertaken.
Copyright © Woodward 1981
All Rights Reserved
Manual 36052 Magnetic Speed Pickup for PG, UG-8, and UG-40 Governors
Magnetic Speed Pickup
for PG, UG-8, and UG-40 Governors
General
The magnetic speed pickup used in the PG-PL, PG-PH, UG-8, and UG-40
governors is a device used to obtain an indication of engine speed without
providing an additional drive pad on the engine. The pickup is installed with the
pole piece 0.003 to 0.007 inch (0.08 to 0.18 mm) from the outside diameter of the
governor ballhead drive gear. As each gear tooth moves past the pole piece, the
external magnetic field produced by the pickup is interrupted momentarily by the
tooth. In the coil of the pickup, this action generates an alternating voltage with a
frequency proportional to the ballhead speed. This variable frequency voltage
may be used in an electrical circuit with a frequency meter or other device to
produce an output indicative of governor or engine speed. Two models of
magnetic pickups are available, “regular” and “explosion proof”.
The two models have an external 5/8”-18 thread which installs in a mating tapped
hole in the PG, UG-8, and UG-40 case. It is necessary to use an adapter to
install the optional 3/4”-20 explosion proof speed pickup on the UG-40 case. The
left side of the PG-PL column is drilled and tapped for a left-hand installation of
the 5/8”-18 magnetic pickup. Right hand installation must be requested.
By rotating the pickup in the tapped hole in the PG column or UG case, the
position of the pickup is adjusted relative to the ballhead drive gear teeth. Jam
nuts are provided to lock the pickup securely in position. Seals are used to
prevent governor oil leakage past the threads of the pickup and the adapter.
Use care when installing connectors to the magnetic pickup. It is
factory preset 0.003 to 0.007 inch (0.08 to 0.18 mm) from the ballhead
gear. Changing this setting may damage the gear and/or pickup,
causing governor malfunction. Do not install junction boxes on
explosion proof pickups.
Because of the machining required on the governor before installation of the
magnetic pickup, the governor should be ordered with the magnetic pickup
installed. For retrofit of governors not previously machined for magnetic pickups,
return the governor to Woodward.
The mating connector for the standard magnetic pickup is MS-3106A-10SL-4S
and is supplied by Woodward. The explosion proof magnetic pickup does not use
a mating connector. It is designed with a 1/2 inch internal pipe thread for a
conduit connection and has two 10 foot (3.0 m) 18 AWG (0.8 mm²) leads
attached.
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Magnetic Speed Pickup for PG, UG-8, and UG-40 Governors Manual 36052
Installation
If the speed pickup is installed in the governor while in the field, it must be
assembled with clearance between the pole piece and the ballhead drive gear
teeth of 0.003 to 0.007 inch (0.08 to 0.18 mm). The output of the pickup varies
inversely with the clearance. Hence for maximum output, use the smallest
clearance possible. The recommended procedure is to turn the pickup clockwise
until it touches the highest gear tooth (ballhead must be stopped), and then turn
the pickup counterclockwise by a known amount. One turn of the pickup
produces a movement of 0.0555” (1.410 mm) for the 5/8-18 thread and 0.050”
(1.27 mm) for the 3/4-20 thread.
Figure 1 shows the pickup as installed in a typical PG governor.
Be prepared to make an emergency shutdown when starting the
engine, turbine, or other type of prime mover, to protect against
runaway or overspeed with possible personal injury, loss of life, or
property damage.
Pickup Output Frequency
In the PG or UG governors, the ballhead drive gear rotates at the same speed as
the governor drive shaft. However, the output signal of the magnetic pickup will
vary in different governors because the gears do not have the same number of
teeth. The number of gear teeth is as follows:
UG-8 Governor ............................................ 17
UG-40 Governor .......................................... 28
PGA, PG-PL, or PG-PH Governor ............... 72
Governor speed should not be confused with engine speed. Drive ratio between
the engine and governor must be considered.
Pickup Data
Regular
Impedance: 260 Ω ±20% at 1000 Hz
Suitable for temperatures up to 250 °F (121 °C)
Explosion-proof
Impedance: 205 Ω ±10% at 1000 Hz
Suitable for temperatures up to 200 °F (93 °C)
UL Listed and CSA certified for:
Class I, Groups A, B, C, and D
Class II, Groups E, F, and G
Parts Replacement
When requesting additional information concerning magnetic pickups or governor
operation or when ordering parts, the following information must accompany the
request:
Governor serial number (shown on nameplate)
Manual number (this is manual 36052)
Part reference number, name of part, or description of part
2 Woodward
Manual 36052 Magnetic Speed Pickup for PG, UG-8, and UG-40 Governors
Figure 1. Standard 5/8” Speed Pickup for PG Figure 2. Standard 5/8” Speed Pickup for UG-8
Column and UG-40 Case
Parts for Figures 1 and 2
Ref. No. Name of Part ................................ Quantity
36052-1 Magnetic Pickup 5/8”-18 Thread ................ 1
36052-2 5/8” Nitrite Thread Seal .............................. 1
36052-3 Washer - .656 ID ........................................ 1
Figure 3. Explosion Proof 5/8”-18 Speed Pickup Figure 4. Explosion Proof 3/4”-20 Speed Pickup
for PG Column and Adapter for UG-40
Parts for Figure 3 Parts for Figure 4
Ref. No. Name of Part ............................. Quantity Ref. No. Name of Part ............................. Quantity
36052-4 Magnetic Pickup - 5/8”-18 Thread 36052-7 Magnetic Pickup - 3/4”-20 Thread
Explosion Proof ...................................... 1 Explosion Proof ...................................... 1
36052-5 5/8 Nitrile Thread Seal ........................... 1 36052-8 Mounting Nut .......................................... 1
36052-6 Washer - .656 ID .................................... 1 36052-9 Thread Seal ............................................ 1
36052-10 Washer - 1.125 ....................................... 1
36052-11 Washer - 1.625 x 2.000 Copper .............. 1
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Magnetic Speed Pickup for PG, UG-8, and UG-40 Governors Manual 36052
Figure 5. Pickup Installed in Typical PG Governor
4 Woodward
Manual 36052 Magnetic Speed Pickup for PG, UG-8, and UG-40 Governors
Figure 6. Outline Drawing, UG-40D with Magnetic Pickup
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Magnetic Speed Pickup for PG, UG-8, and UG-40 Governors Manual 36052
Figure 7. Outline Drawing, UG-8D with Magnetic Pickup
6 Woodward
Manual 36052 Magnetic Speed Pickup for PG, UG-8, and UG-40 Governors
Woodward 7
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Please reference publication 36052A.
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