Rice Lake PW 400, PW 500 Installation And Service Manual
PW 400 / PW 500
Portable Wheel Load Weigher
Installation and Service
Manual
37881
Contents
1.0 Introduction .............................................................................................................................. 1
1.1 General Description.................................................................................................... 1
1.2 Functional Description................................................................................................ 1
1.3 Physical Description ................................................................................................... 2
1.4 Options and Accessories............................................................................................ 2
2.0 Operation .................................................................................................................................. 3
2.1 Portable Weighing Procedures................................................................................... 3
2.2 Transient Weight Shifting ........................................................................................... 3
2.3 Selection of Weigh Sites............................................................................................. 3
2.4 Wheel Placement ....................................................................................................... 4
2.5 Controls and Indicators............................................................................................... 4
2.6 Reading the Weigher Display..................................................................................... 5
2.7 Operating Instructions ................................................................................................ 6
2.8 Local/Total Operation ................................................................................................. 6
2.9 Weigher Bus Address................................................................................................. 7
3.0 Maintenance............................................................................................................................. 8
3.1 Recharging the Battery............................................................................................... 8
3.2 Removing the Platform............................................................................................... 9
3.3 Removing Links.......................................................................................................... 9
3.4 Removing the Display Cover...................................................................................... 9
3.5 Removing the PC Board........................................................................................... 10
3.6 Removing the Battery............................................................................................... 11
3.7 Inspection and Cleaning........................................................................................... 11
3.8 Inspection Prior to Assembly.................................................................................... 11
3.9 Lubrication................................................................................................................ 12
3.10 Reassembly.............................................................................................................. 12
3.11 Installing the PC Board............................................................................................. 12
3.12 Reassembling the Display Cover ............................................................................. 12
3.13 Reassembling Links ................................................................................................. 12
3.14 Reassembling the Platform ...................................................................................... 13
4.0 Calibration Verification .......................................................................................................... 13
5.0 Calibration Instructions.......................................................................................................... 14
6.0 Replacement Parts ................................................................................................................. 16
7.0 Wiring Diagram ...................................................................................................................... 18
PW 400 / PW 500 Limited Warranty................................................................................................... 19
Copyright ©1997 Rice Lake Weighing Systems. All rights reserved. Printed in the United States of America.
Specifications subject to change without notice.
January 1997
1.0 Introduction
This manual contains operating and service procedures for both the PW 400 and PW 500 Portable Wheel
Weighers.
1.1 General Description
The PW 400 and PW 500 Portable Wheel Weighers are microprocessor controlled, hydraulically operated,
static weighers designed to measure weight applied anywhere within the weighing surface. The weighers are
packaged in a rugged, corrosion resistant, lightweight enclosure specifically designed to meet the demand of
daily outdoor operation.
The PW 400 and PW 500 are identical in operation. The main difference in the two models is the size of the
platform. The PW 400 platform is 10" x 11" to handle most standard truck tires, while the larger PW 500
platform at 13.5" x 11" is suitable for trucks with oversize tires or dual wheels. Both the PW 400 and PW 500
in 20,000 lb capacity x 50 lb display division models are NTEP certified Class IIII for commercial use.
Each weigher is powered by either a rechargeable or non-rechargeable battery. A variety of optional charging
units are available for the rechargeable models, allowing them to be charged from 110 VAC, 220 VAC, or 12
VDC power sources.
The units have 20-degree integral ramps that allow for easy drive-on/off and a nonskid bottom for operator
safety. Optional larger approach ramps are available to give a more gradual approach slope and longer
footprint.
Weighers can be used in one of two modes:
1. In Local mode, each weigher displays only its own load.
2. In Total mode, multiple weighers can be interconnected in series to allow as many as 30 units to be
used together. Each weigher displays the total weight of all interconnected weighers.
Initial calibration of each weigher is performed at the factory and no field adjustments are necessary.
Recalibration is necessary only after repair or replacement procedures.
1.2 Functional Description
The weight applied to the platform of the weigher undergoes a series of transformations before being displayed to the operator. The first transformation is the weight becoming a directed force transferred by a series
of mechanical links to a single hydraulic load cell fitted with an electronic pressure transducer.
The load cell contains a non-compressible fluid that exhibits a known viscosity over the operating pressure
and temperature range. Any change in pressure is detected by the pressure transducer which supplies an
electrical signal that is proportional to the weight applied to the weigher platform.
The electrical signal is converted to a digital format that is transmitted to the microprocessor. The microprocessor decodes the digital signal and transmits the weight information to the display.
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1.3 Physical Description
Overall length 20 1/2 inches
Width, main body 14 inches
Width, including handle 17 3/4 inches
Width, weighing surface 10 1/2 inches (PW 400); 13 1/2 inches (PW 500)
Length, weighing surface 11 inches
Height, nominal 3 inches
Height, maximum 3-1/8 inches
Ramp slope angle 20 degrees
Weight, complete unit 46 pounds (PW 400); 50 pounds (PW 500)
Weighing capacity 20,000 pounds / 10,000 kilograms
Accuracy As per NIST Handbook 44
Approvals 20,000 lb x 50 lb models are NTEP-certified
±50 Lbs. (0–2,500 lbs.)
±100 Lbs. (2,501–10,000 lbs.)
±150 Lbs. (10,001–20,000 lbs.)
Class IIII, CC #96-166, n
max
= 400
Operating Temperature Range 0–120°F
Storage Temperature -35–150°F
Humidity (Operating and Storage) 100%, non-condensing
Power Requirements 12 VDC
1.4 Options and Accessories
The following table shows the options and accessories available for the PW 400 and PW 500 Portable Wheel
Load Weighers. Battery chargers listed in the table show the required power source and the number of wheel
weighers that can be charged using the listed charger.
SWLR
yrosseccA/noitpO
004WP,spmarhcaorppA09273
005WP,spmarhcaorppA19273
elbacnoitacinummoC
)tcennocretnilatot/lacolrofderiuqer(
elacs-1,CAV021,regrahCyrettaB58273
elacs-2,CDV21,regrahCyrettaB68273
rebmuNtraP
98273
elacs-4,CDV21,regrahCyrettaB78273
elacs-6,CDV21,regrahCyrettaB88273
2
2.0 Operation
2.1 Portable Weighing Procedures
The PW 400/PW 500 Portable Wheel Load Weigher is specifically designed to indicate the weight of an
individual wheel resting at any position within the weighing area. The operator must follow the basic principles of portable weighing in order to obtain accurate and reliable results. Improper weighing procedures can
induce errors into the weighing process that are no fault of the weigher.
Accurate vehicle axle or gross weight cannot be arrived at by measuring a single wheel, a single side, or a
single axle within an axle group. An axle group is defined as any group of axles that share a common linkage
between them, whether it be mechanical, hydraulic or pneumatic. Both sides of any axle must be weighed at
the same setting. In the case of a tandem axle group, all four wheels must be weighed at the same setting.
The PW 400 and PW 500 weighers are precision weight indicators. By using correct techniques, excellent and
dependable results will be achieved.
2.2 Transient Weight Shifting
The largest single factor determining the accuracy of portable weighing is transient weight shift within the
vehicle itself.
Transient weight shifting can best be defined as weight which is transferred from one axle to another due to:
• Placing one axle in an unusual attitude in relation to another by lifting off a normal plane.
• Placing the vehicle in a non-level position due to poor approach or poor choice of weigh site.
• Physical contact of tire with ground.
Axles are naturally lifted off a normal plane any time that the weigher platform is above ground level. The
amount of transient weight shift is a direct function of the distance that the axle is lifted. Using the correct
number of weighers reduces transient weight shift to a minimum. Hence, reducing the number of consecutive
weighments required will result in a more accurate weighing. Axles spaced within 12 feet or closer should
always be weighed at the same setting.
The balance of the transient weight shift may also be compensated for by placing simple blocks, approximately 3 inches in height, under the conflicting axle so as to create a level plane.
Example: When single or tandem drive axles are weighed, the steering axle should be elevated to the same
level as the weigher platform. When the steering axle is weighed, drive axles should be elevated to platform
level. This also applies to coupled trailers with short axle spacing.
The transient shift between drive axles and most trailer axles is normally insignificant and no blocks need be
used.
2.3 Selection of Weigh Sites
Selection of a suitable weigh site is a prerequisite to accurate weighing. Ideal weighing sites should be flat,
level and hard surfaces. Approaches should be long enough for a straight-line movement of the vehicle prior
to and during the weighing. Realizing the problems of finding ideal weighing surfaces, the PW 400/PW 500
weigher is designed to weigh on a side slope, not exceeding 3 degrees, and on any relatively flat surface
capable of holding the weigher above ground. The site chosen should not be up- or downhill, in a hollow or
on a crest, as these conditions will redistribute the weights of the axles.
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2.4 Wheel Placement
Correct wheel placement is necessary for accurate weighing of vehicles. For best results, the ramp approach
of each weigher should be firmly seated against the tires and the weigher platform centered with the wheel
prior to driving the vehicle onto the weigher.
Occasionally the outside tire has such low air pressure that the inside tire of a dual set does not clear the
ground. This will give an erroneous reading since the inner tire is bearing part of the load. The PW 400/PW
500 weigher design is such that either tire may be used. To weigh inside tires, turn the weigher 180 degrees
and continue weighing. The sum of the wheel weights will still equal the axle weight.
Experience is the real key to successful portable weighing. Incorrect weighing results can usually be attributed to improper procedure. Following these basic rules of portable weighing will insure the best possible
results.
2.5 Controls and Indicators
Figure 1 shows the weigher display and controls conveniently located on the handle side of the weigher. The
display is a 1 line, 16 character, alphanumeric liquid crystal display (LCD) with a magnified character height
of 1/2 inch. The display is backlit for night time operation of the weigher.
Operational switches and connectors are shown in Figure 1 and function as follows:
LCL/TTLRST-OFF/ON ZERO COMM CHGRDisplay
Figure 1— Controls and Indicators
RST-OFF/ON
This is a sealed, double-pole, double-throw momentary toggle switch.
Press the switch to the right and release to turn the weigher ON.
Press the switch to the right again and release to turn the weigher OFF.
ZERO
This is a sealed, momentary push-button switch.
Press the switch to ZERO the display before weighing.
LCL/TTL
This is a sealed, momentary push-button switch. Press the switch to toggle between the LOCAL and
TOTAL modes. (Requires two or more weighers be connected together via communication cable).
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ZERO and LCL/TTL
Activates or deactivates the display backlighting. Press both buttons at the same time to turn the display
backlighting ON or OFF.
COMM
Communication connector for connecting two or more weighers together for Local/Total function or
remote communications.
CHGR
Connection for input to recharge weigher battery.
Maximum charge is 13.5 VDC at 300 mA
2.6 Reading the Weigher Display
The PW 500 weigher is capable of indicating informational messages to the operator as well as the weight
value. These messages and their meaning are given below:
OUTPUT MESSAGE MEANING
“
BUS ADDRESS = # #” Number assigned to weigher communication functions.
“CALIBRATE ZERO” Unit performing zero function.
“# # # # # LB” Local weight in pounds.
“# # # # # KG” Local weight in kilograms.
“MOTION ERROR” Failure of unit to achieve a stable zero setting.
“RANGE ERROR” Weigher output exceeds zero range capability.
“OVER-RANGE” Weigher output exceeds capacity of weigher.
“LOW BATTERY” Intermittent message meaning battery is becoming low.
“RECHARGE BATTERY” Battery too low to provide accurate weight indication.
“## TOTAL SCALES” This message is followed by the number of weighers within
“BAD COMM ADDRESS” The address number assigned to each weigher is duplicated
“NO SCALES ANSWER” None of the weighers connected can communicate with any
” Displayed at power up.
Recharge at first opportunity.
Recharge before use.
an interconnected group.
within the group.
other weigher.
“NO COMM RESPONSE” Communications interrupted between two or more weighers.
“FORCED TO LOCAL” Weigher has returned to LOCAL weighing mode due to
interruption or lack of communication response.
“NEW ADDRESS = # #” Acceptance of new address number assigned to weigher.
“RELEASE ZERO” Message to operator to remove hand from ZERO button.
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