Strong GR4 Reference guide

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Type:____Placer_______________
Model:_______________________
Serial Number_________________

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Operations and Procedures Manual
Strong Manufacturing Co., Inc.
Placer
Strong Manufacturing Company, Inc.
Specializing on Lightweight Cementitious Mixing and Pumping Equipment
2301 University Drive, PO Box 8068, Pine Bluff, AR 71611
[phone] –800-238-5042 –Fax [phone]

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Table of Contents
I. Preface 4
II. General Safety Information 5-9
III. Components 10-
1. Engine 10
2. Mixer 11
3. Material Pump 12-13
A. Rotor and Stator 12
B. Suction Housing 12-13
C. Drive Assembly 13
4. Loading System 14
5. Hydraulics 15-18
A. Maintenance 16-17
B. Trouble Shooting 18
6. Grout Machine Trailer 19-22
A. Troubleshooting 21-22
IV. Operations 23-28
1. Setting Up 23-25
2. Mixing and Pumping 25-26
3. Clean-Up 26-28
V. Master Parts List 29
VI. Manual Drawing List 30-

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Preface
The Strong Model GR4 Grout Machine is specifically designed to convey, mix and pump cementitious
slurries with a high concentration of sand aggregate. To best facilitate the handling of sand, a
hydraulically powered skip bucket is used to transfer both the cement and sand from ground level up to
the mixer and then dumped.
We are confident that your new Grout Mixer-Placer will increase profits, but the life and service received
from it will depend to a great extent on the care and attention you give it during daily and routine use.
This OPERATION & MAINTENANCE MANUAL has been provided to assist you in obtaining the
utmost from your machine and to instruct you and your operating personnel it its SAFE and efficient use.
This Manual should be carefully read and its instructions adhered to by those who will be responsible for
the operation, maintenance, transportation, and uses of the machine. You should remember that the
nature of your business –that is, the mixer and pumping of Gypsum or cement and sand aggregates,
water, and admixtures –creates the most severe conditions under which machinery can operate. It was
with these conditions in mind that the selection and design of the various components were made.
A separate section immediately following this Preface contains specific safety information. No one
should be permitted to perform any function on the machine unless he or she has read the safety section of
this Manual. The safety section is also available free of charge to owners of the Model GR4 Grout
Machine as a separate pamphlet by writing the Strong Manufacturing Company, PO Box 8068, Pine
Bluff, Arkansas 71611.
Following the safety section are descriptions of the function of the machine, its operation, various
systems, maintenance information, and so on. In order to help you properly service and care for the
machine, the operation and maintenance manuals from the various suppliers of components are included.
These should be carefully read and followed by those who will be responsible for maintenance of the
machine. The information given will help you produce a better and more profitable product.

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Notice
The specific Safety Rules are important and should be read, understood, and followed by anyone who will
operate, use, or work around the Grout machine. They will alert you to changes and procedures of which
you may not be aware. In addition, it would be best to read the entire Operations Manual before using or
working on the machine. If you observe anyone operating in non-conformance with these rules and
procedures, inform them and the person in charge. Safety is your responsibility. Copies of this Safety
Section are available free on request, at any time, by writing to: Strong Manufacturing Company, Inc., PO
Box 8068, Pine Bluff, Arkansas 71611. Please include the serial number(s) of your machine(s) with your
request. Additional copies of the entire Operation and Maintenance Manual can be obtained at the above
address for the charge of $30.00 each.

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Important
General Safety Information
The Strong Manufacturing GR-4 Grout Machine is primarily used for the mixing and pumping of
Gypsum or cement, sand and water slurry. In addition to the usual hazards of machinery, several special
hazards are involved in these operations.
1. Do not reach into the mixer without first shutting off the engine and removing the key from the
control panel. Also, place all hydraulic valves in the center or neutral position.
2. Make certain the Skip Bucket is in the full upright position for travel and the safety pin is
installed. Failure to do this could allow the bucket to shake down during travel and become over-
width. This would create a dangerous situation possibly resulting in property damage, personal
injury or even death.
3. Do not disconnect material hose with hoses under pressure. Always run pump in reverse until
pressure gauge reads “0” PSI, or hoses become soft. Failure to do so could result in material
blowing out under pressure and striking someone causing bruises, cuts, breaking of limb or
possible loss of sight if material enters eye.
4. Because of wear and weathering that occurs on material hose, the following teat should be
conducted at the beginning of each day to determine the conditions pf the hose.
The field test consists of the following:
a. Attach all of the sections of hose which will be used in the day’s operation together just as
they will be used.
b. Pump water into the hose until it begins to discharge.
c. Cap the discharge end securely with Test Cap.
d. After advising all personnel to stand clear of the hose, operate the pump in 1st gear until the
pressure indicated on the pressure gauge registers the maximum pressure the pump will
produce and hold this pressure for 30 seconds.
e. Reverse the pump until “0” PSI pressure indicates on the gauge and the discharge hose
becomes soft. (See also Rule No. 4)

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f. Remove the cap. Operate the pump until the water has been discharged and then proceed
with the pumping of the slurry.
This field test should be repeated if any damage or accident befalls a section of the hose or if, for
any reason, a section is suspect.
All replacement material hose should not be less than 800 PSI tested. Such hoses can be obtained
from Strong Mfg. Co. If a local supplier is used, the following brand and model numbers are
appropriate:
•Gates Rubber Company –1 ½” plaster hose 800 PSI working pressure – Product
#33280015
•Acme Hamilton Mfg. Corp. –1 ½” plaster hose 800 PSI working pressure Spec. No. 39-
9126
Do not use other hoses unless specifically advised by the Strong Manufacturing Company that
they are adequate.
Caution: Do not operate the machine unless a properly functioning pressure gauge, which is
supplied with the machine for use at the discharge end of the pump, is attached. This gauge
allows the operator to prevent excessive pressures which could cause the hose to burst.
Caution: Never use weathered, rotten, or damaged hoses with damaged fittings in conjunction
with pumping operations. They represent a hazard to operators, bystanders, and persons handling
the hoses. If a hose should burst or a fitting let go under pressure, persons could be injured.
Caution: When removing a section of hose, pressure must be relieved before undoing a fitting.
This can be done by putting the pump in reverse and running it slowly until the discharge hose at
the pump becomes soft*. Failure to do this will result in the hose being under pressure when the
fitting is undone, and material being blown out when disconnected striking the face & eyes with
the danger of injury by striking.
*When pumping in reverse, be sure that materials are coming back into the hopper as evidenced
by the materials level in the hopper rising. Watch the discharge hose to avoid collapsing it and
causing the pump to run dry.
5. Never run the materials pump dry because just a few minutes of running dry will ruin the pump
stator. Always have water or slurry in hopper when running pump.
6. If plug-up occurs, or a section of hose is to be removed, the hose pressure must be relieved before
uncoupling a fitting. This is done by running the materials pump in reverse slowly, until the
pressure gauge on the pressure assembly reads “0” PSI. Failure to do so will result in material
under pressure “blowing out” when uncoupled, resulting in possible bruises, lacerations, and most

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dreadfully, the potential of material blowing out into the eye causing injury or even loss of sight.
7. It is possible for excessive hydraulic pressure to develop if hydraulic line is blocked. Extreme
care should be exercised while working on this hydraulic system –damage to equipment and/or
injury may result from misuse or careless operation of these components. Never loosely block off
a hydraulic line. If a pipe plug or cap is used when testing hydraulic components, be sure it is
tight –it can become a deadly projectile.
8. Each hydraulic system is provided with a pre-set relief valve. This valve is pre-set at pressure
lower than the maximum the various hydraulic components are rated. ONLY Strong
Manufacturing personnel or persons with experience in hydraulics should adjust the relief valve.
If the relief valve is adjusted to pressures exceeding the rating of the components used, the
components can rupture or explode in a high-pressure situation. A motor, or hose exposed to
greater pressures than it is rated for, can become a deadly projectile, resulting in broken bones,
lacerations and even death.
9. Properly operating hydraulic pressure gauges should be on the machine at all times. These
gauges provide an instantaneous read-out of hydraulic pressures required to power the system.
Relief valves can malfunction. If hydraulic pressures ever exceed factory settings –the machine
should be stopped immediately. Get relief valves replaced or properly adjusted only be Strong
Manufacturing personnel or by people experienced in hydraulics. Without proper operating
pressure gauges, malfunctioning relief valves cannot be determined; therefore, exposing
personnel to potential injury caused by a component rupturing or exploding.
10. Be sure all machinery guards are in place. The guards provided with this machine consist of the
following:
•Mixer inlet guard
•Mixer drive motor guard
•Mixer splash guard
•Wet materials hopper guard
•Engine side panels
As a general rule, the machine should be kept as clean as possible. Material should not be
allowed to build up on warning signs, instructions, gauges, etc. It is also possible that material
buildup could interfere with control operation thus presenting hazards of a general nature.
Caution: Do not stand under or near the skip bucket at any time. Possible injuries such as cuts,
bruises, broken limbs, or death could occur, if struck by the skip bucket while it is being raised
and lowered.

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WARNING
Failure to follow these instructions may result in wheel loss which can cause injury or death!
Torque wheel nuts to 90-120 lb-ft before first road use. Retorque to 90-120 lb-ft after 10, 25, and 50
miles. Check periodically thereafter.
SAFETY
Cleaning, Repairing, Servicing and Adjusting Prime Movers, Machinery & Equipment
Section 3314 –General Industry Safety Orders
Machinery or equipment capable or movement shall be stopped and the power source de-energized or
disengaged, and, if necessary, the moveable parts shall be mechanically blocked or locked to prevent
inadvertent movement during cleaning, service or adjusting operations unless the machinery or equipment
must be capable of movement during this period in order to perform the specific task. If so, the
EMPLOYER shall minimize the hazard of movement by providing and requiring the use of extension
tools (e.g. extended swabs, brushes, scrapers) or other methods or means to protect employees from injury
due to such movement.
Employees shall be made familiar with the safe use and maintenance of such tools by thorough training.

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Engine
The power unit is either a Cummins diesel or a Ford gasoline engine. These water-cooled engines are
designed for industrial application and are the best engines for the job. The engine is also the most costly,
single piece of equipment on the machine. When referring to the manual for service recommendation, use
those given for the most severe conditions.
The engine speed is pre-set for optimal performance. Never slow the engine RPM down when pumping
under full load, as this will cause the engine to “lug”, setting up high cylinder head temperature and
causing engine damage.
The engine is equipped with a full range variable speed governor. This means that at a given throttle
setting, the engine will maintain a given PRM unless overloaded. When the engine RPM falls off, it is
caused either by load being greater than the engine can carry or the engine is not developing its required
horsepower. When this occurs, check to see that the pumping pressure is not too great as caused by a
restriction in the lines or a mix too dry. The other possibility is the engine not getting fuel properly, or the
air intake could be restricted.
The engine has been serviced with a break-in oil which should be changed after 40 hours of service and
replaced with a good grade of engine oil. (e.g. Rotella). (See engine owner’s manual for
recommendations for your engine and operating conditions).

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Strong-Mater Mixer
(Dwg. #86000007)
The Strong-Mate Mixer is a completely new idea in mixers...designed for mixing most varieties of
cementitious materials. The Mixer is designed to give a MAXIMUM amount of agitation, complete
dispersement of the cement sand, and admixtures in as short mixing cycle as is possible.
To accomplish this, we use two inter-connected fixed drums with two self-wiping ribbon paddles that
counter-rotate. The mix is brought to the center where it gets an EXTRA ORDINARY and VIOLENT
mixing action –but does no “beat” the mix as is the case with the conventional types paddle mixers. The
amount of mixing time to bring the mixture into a completely homogeneous mix under normal conditions
is 15 to 20 seconds.
When it is necessary to stop the machine or to delay dumping a mix, the Mixer should be stopped from
rotating. Mixer should be thoroughly cleaned after each day’s use to prevent a buildup of cement on
blades and walls of Mixers.
The Mixer has a set of packing chambers with 5 rings of packing, at either end of blade shafts to prevent
water and the mix from getting into the flange bearings. One fitting, on each of the flange bearings, is for
greasing the seals inside. THESE FITTINGS ARE LOCATED ON TOP OF THE BEARING
HOUSING. These should be greased every four hours of operation and at the end of each day’s
operation. Enough grease is injected to show at the end of the packing housing inside of Mixer after the
washing up operation. This insures that any materials that have worked past the seals is discharged out
and cannot harden inside and prevent the sealing action.
Grease the fittings on the sides of the bearing housing every six months. These fittings are provided for
greasing the race of the bearings and are pre-packed at the factory. Too much grease here can shorten the
life of the bearing more than not greasing it at all.
Caution: DO NOT remove mixer guard or put hand in mixer in any way without stopping the engine and
removing the ignition switch key. Always put mixer hydraulic control valve in neutral prior to stopping
engine and checking to see if it is in neutral prior to starting engine. When cleaning mixer at end of day’s
operation, it is necessary to wash out loose materials removed during clean-up. REPLACE the mixer
guard before starting engine. Failure to do so could result in severe bodily injury.

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Strong-Master Pump
Dwg. #86000020
The Strong-Master pump consists of three principle parts, i.e., the pumping elements, the suction housing
for material storage and the drive assembly to transfer power to the pumping elements.
The pumping elements for the grout machine consists of a 2R10-0 rotor and stator connected to the
suction housing. This rotor-stator combination is capable of producing 400 PSI pressure when new.
Pressure of this amount will not be encountered during normal operations, UNLESS a “plug-up” in the
hose occurs. When pressure of this amount occurs, stop the pump, put in reverse and relieve pressure.
Find the “plug” in hose. Remove and clean the plugged section of hose. As the pump is operated, the
rotor and stator will wear, causing the pressure to drop and discharge to fall off. Should either rotor or
stator have excess wear it will shorten the life of the other part considerably. Worn parts cause “slippage”
within the pumping elements which accelerates the wear. Generally, the stator wears first. With some
grades of sand, the life of the stator could be as little as 300 yards, or about 600 batches. To prolong the
stator life, change ends after about 250 yards, or 500 batches. Generally, two stators can be used with
each rotor. Check rotor for wear with stator removed to see that is has uniform wear. If wear is
excessive, the chrome will be worn off the lobes of rotor, usually at discharge end. When this occurs,
replace rotor. Worn rotors will result in reduction of stator life by one-half or more. Never use a new
rotor with worn out rotor. When wear is excessive, the material flow from hose will decrease and become
intermittent. When flow breaks, s small puff of vapor comes out. At this point, the rotor and stator
should be examined and one, or both, replaced if wear is observed.
To remove the stator, loosen the “U” bolt clamp and break the joint with a pipe wrench. The stator can
then be screwed out of threads by rotating the rotor slowly. After the stator is out of the threads, replace
the pipe wrench and hold the stator from turning; and again, turn the rotor. The stator will “worm-off”
the rotor. To replace the stator, reverse this procedure and use the machine power to turn the rotor.
Caution: When using a pipe wrench to hold the stator be sure the pump is turning at the lowest
speed possible. Stay clear of the pipe wrench.
The suction housing has the material hopper bolted to it. A connecting rod connects the rotor to the drive
shaft at the hub inside the suction housing. The connecting rod has a section of auger flighting bolted to it
to keep materials agitated during operation. These parts operating in a sand-gypsum, or cement slurry,
are subject to severe wear. The connecting rod should be inspected for excess wear at the pinholes every

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400 hours of operation or more often after wear begins. It is easily done when the rotor is removed as one
end is usually greatest so that it is not necessary to remove other end unless pinholes show wear. Inspect
and replace worn pins and boot seals whenever rotor and/or connecting rod is inspected. Also, inspect the
holes in both the rotor and drive shaft hub for wear. There are two sets of holes in each, so that an
alternate pair of holes can be used when wear is excessive on one set of holes. When both sets of holes
are worn, the drive shaft hub should be replaced.
Connected to the suction housing is the drive assembly that houses the packing chamber and chrome
sleeve, drift shaft and bearings. The bearings should be greased every 40 hours of operation only. The
packing chamber should be greased twice daily and always at the completion of the day.
Dismantling and Installing Pump Drive
Remove hydraulic motor from drive assembly adaptor or gear box from shaft depending on hydrostatic or
mechanical drive. Remove square head from drive collar. Loosen boot clamps, and slip off end boot.
Roll boot drive from collar. Remove four ½-inch bolts holding bearing housing to suction hopper.
Remove bottom half of frame cradle. Loosen set screws and fastening bolts on top half of frame cradle.
Entire unit will now lift clear of the suction hopper. There is approximately 1/16th-inch clearance all
around between the drive collar and the center hole into the suction hopper and plate. Set-up concrete
may block passage of drive collar through the housing. To install new unit, reverse the above procedures,
following the steps below. It is important to set frame cradle to bearing housing last in order, not to place
strain on it. Pack drive collar and Esso Nebula EP2 or equivalent grease. On the bearing housing is a
raised boss which fits into a counter bore in the suction hopper bolting face. Examine both of these
sections for burrs. Remove with flat mill file. Make sure all foreign matter is removed from all mating
surfaces. Wipe with grease after cleaning. Pull the four housing bolts up alternately, so that housing
faces contact all around. After drive unit is secured in place, tighten frame cradle set screws until cradle
is firm against bearing housing. Tighten lock nuts and mounting bolts. Complete balance of assembly in
reverse order of dismantling.

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Loading System
Dwg. #11144001
A hydraulically powered bucket is used to transfer the cement and the aggregate from the ground, and
dumped into the mixer.
The bucket is secured in the travel position by a pin through the bucket arm.
Caution: Failure to install SAFETY PIN prior to travel could result in the bucket falling causing
extensive damage to the machine and possible personnel injury.
The bucket is hydraulically operated. A directional control valve is used to divert oil flow to a cylinder.
The operator engages the control valve handle to determine direction of bucket travel. NOTE: See
hydraulic section for more detail.
The bucket is raised to the upper limit of travel and the valve released. The dump valve is then engaged,
and the bucket dumps the material into the mixer. The procedure is then reversed for lowering the bucket
to ground level.
Always raise the arms to their upright position before tilting the bucket. When lowering the buckets
return the bucket to the upright position before beginning the decent of the arms.

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Hydraulic System
The hydraulic system consists of the following components:
Refer to drawing #86000231.
WARNING:
The hydraulic pump is driven from the crankshaft of engine and is operating at all times the engine is
running. Whenever the machine is not in use, or when working on any part, stop the engine and remove
the red ignition key to eliminate any danger of mixer being started, or skip bucket being lifted. Prior to
starting engine, check to see that all control valves are in a neutral or off position. Failure to do so could
cause someone working on, or around machine, to be trapped by a moving part and injured seriously.
Located on the operator’s platform/panel, are the control valves. To operate operator should become
familiar with operation of these valves prior to starting the operation of these valves prior to starting the
operation, so he can start and stop without hesitation.
The skip bucket is actuated by two control valves on the operator’s panel. One valve raises and lowers
the bucket, and one controls the tilt of the bucket to dump material into the mixer. These two valves
control the flow of oil into and out of hydraulic cylinders.
Optionally, on the rear of the machine on the operator’s side is a control valve to direct the flow of oil to a
hydraulic motor which can start, stop and reverse the hose reels. To unreel the hose the valve is lifted
“up”, to reel hoses in, the valve is depressed “down”.
Also in the system are pressure relief valves. These control the hydraulic pressure that can be exerted to
the various components and thus the force. These have been reset at the factory and should not be
adjusted without consulting Strong Mfg. Co., or a qualified hydraulic mechanic. Further discussion of the
hydraulic system and components to follow.

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Hydraulic System
(Maintenance)
The hydraulic system must be kept free of dirt. Inside the tank is a strainer mounted on the pump suction
line. If it becomes clogged, the pump will malfunction due to starvation. Also, damage to the pump will
occur if starvation continues. Any increase in the noise of the system, while no load applied. May
indicate this condition. This strainer should be checked after the first 100 hours and thereafter every six-
(6) months or anytime a hydraulic component is replaced. To service the strainer, unbolt and gently lift
the cover plate from the tank. This cover is directly over the strainer in the bottom of the tank. The
strainer is connected to the suction line with pipe threads, turn it counterclockwise several turns and it will
come out. Rinse the strainer in a nonflammable cleaning fluid using a paint brush to loosen sludge on the
screen. If the screen shows any breaks, replace.
Suction line threaded connections must be maintained airtight. Use semi-head Permatex, Teflon tape or
other oil proof compound. Keep compounds out of line. Teflon tape is preferred since it will not damage
the hydraulic system.
Approximately 30-60 gallons of hydraulic oil, Mobile DTE 10 the same as used in original installation,
should be maintained in the reservoir. (Tank size determined by final drive configuration.) The tank is
equipped with an oil level indicator. Never allow the oil level to be less than the “low” mark of the sight
gauge mounted at the end or side of the hydraulic tank.
Overheating of oil will occur if storage level drops too low. Condition and color of oil should be
checked. Change oil when considerably darker than new oil. Also, check oil temperature occasionally.
It should not be more than 150 degrees Fahrenheit during last half of workday. A thermometer is part of
the hydraulic sight gauge. One hundred thirty (130) degrees is uncomfortable to touch. Oil dangerously
hot is too hot too touch.
All hoses should be checked periodically for signs of failure. It is very important to keep close check on
the pump suction hose. Check for soft spots or breaks. The oil used in the system is Mobile DTE 10.
The hydraulic system is composed of either one or two independent circuits. (A circuit diagram is
enclosed). One circuit provides oil for the mixer motor drive, bucket drive, bucket tilt and material hose

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reel drive. The other circuit powers the material pump (on hydrostatic units). The flow of oil is
controlled by a series of hydraulic valves.
When trouble in the hydraulic system exists, it is usually accompanied by excessive heat. The major
sources of trouble are worn parts in the pump and/or motor causing excessive slippage and heat, oil too
thin and breaking down causing excessive slippage, and worn valves parts or broken “O” Rings causing a
by-pass. To find where trouble exists in a system, see the Trouble Shooting section that follows.

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Trouble Shooting
(Hydraulics)
Problem: Excessive Heat
Problem
How to Determine
Solution
Worn parts in hydraulic pump
and/or hydraulic motors.
Measure oil temperature should
not exceed 150F. If
thermometer is not available
place hand on storage tank –
130F is uncomfortable.
Determine pressure by
following procedure.
Oil too thin and breaking down,
causing excessive slippage.
Worn valve & parts or broken
“O” rings causing a by-pass.
Oil level too low.
Check sight gauge.
Add oil.
Operating pressure too high.
Check pressure gauge.
Eliminate some of load.
Trouble Shooting Procedure
•Break and plug a line at the control valve between the hydraulic pump and control valve, but
downstream from pressure relief valve.
•Insert 0-3000 PSI pressure gauge in line.
•Start engine and run at idle speed and clutch disengaged.
•If pressure does not put up 2000 PSI of pressure, pump is worn, or relief valve is set too low.
•To check relief valve, remove acorn nut and screw in on the slot headed screw. Do so until
pressure gauge reads 2000 PSI.
•If at this time pressure does not rise to 2000 PSI, hydraulic pump is worn and should be replaced.
•If pump produces sufficient pressure, insert pressure gauge between control valve and motor.
•Disconnect hydraulic line nearest valve foot pedal and insert pressure gauge. Plug line at motor.
•Push control valve forward and read hydraulic pressure.
•If pressure does not come up to 2000 PSI, control valve should be replaced.
•If relief valve and pump have checked out, the problem is the motor and should be replaced.

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Grout Machine Trailer
The trailer is equipped with 6000-pound capacity axles with brakes on both axles, electric brakes are
standard, however, hydraulic brakes may be furnished on request. The standard hitch is a 2-5/16”
diameter ball with option for Lunette eye. Tires are 235/85 R16 L.R.E. radials. Trailer weight with
equipment is approximately 8800 pounds.
The trailer is equipped with a breakaway safety switch with electric brakes. For hydraulic surge brakes a
small chain is attached to some point on tow truck hitch line with and behind the ball hitch. This should
only have a small amount off slack in cable so that in the event of the trailer disconnecting, the chain will
actuate the master cylinder thus applying full brakes at shortest possible travel. For electric brakes the
safety switch has a small cable to connect to tow truck that will pull a plug in electrical switch located at
front end of trailer. Before moving trailer onto road or highway, the system should be checked to see if
operating properly. To do this, pull the safety cable that attached to towing truck. For either electric or
hydraulic surge brakes, this should cause the wheels on the trailer to lock and prevent wheels from turning
when towing truck pulls on trailer. If brakes fail to lock, check system for cause.
If hydraulically operated, check master cylinder on surge hitch for proper fluid level. Refill and bleed as
with any hydraulic brakes system, until brakes are operating satisfactorily. When bleeding system, start
on wheel cylinder farthest from the master cylinder. Release sufficient fluid to assure that all air is
removed from the line. Then bleed each wheel cylinder. When properly operating, the pressure applied
to the master cylinder will indicate a firm “pedal” when brakes are applied. If “spongy”, it indicates air is
still in the line. When necessary to add brake fluid, a careful check should be made to see if any lines or
connections are leaking, or a wheel cylinder is leaking. When holding a firm pressure on the master
cylinder, if these is a leak in the system, then the master cylinder will depress or move slowly. Replace
lines, connections or wheel cylinders when leaking. If no leaks are found but the brakes still do not
function after the bleed, then the probable cause is in the master cylinder. The master cylinder should be
checked monthly and refilled with a good brand of brake fluid, same as used in towing vehicle.
When trouble exists in the electrical brake system it is generally caused by bad electrical connections.
Check the electrical plug on the rear of the towing vehicle with a test light or preferably with a voltmeter.
When moving the hand lever on the actuator in the cab of the tow truck a current should be produced.
The current should increase when moving the hand lever. If no current is indicated, trouble is in tow
vehicle. If a current is at the connection from the truck to the trailer and no brakes, check prongs on the
electrical connector and spread open with the blade of a pocket knife to cause firm contact in plug. Check

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to see if the ground wires as well as other wires are in contact. If all wiring checks out all right, remove
the wheel and drum and see if the wiring inside of tire wheel is intact. Check the magnetic actuator for
excessive wear. By using a steel object, check the magnet when applying the hand lever in the tow
vehicle to see that a strong magnet exists. If not, replace magnet actuator. Adjust brake shoes every
10,000 miles or six months as described above.
The wheel beatings should be inspected and repacked with a good grade of wheel bearing grease every
six months. Inspect all wiring and lights and replace when showing wear or damage.
Caution: After hooking the trailer to the towing vehicle and before driving away, check closely the
following:
1. Trailer hitch to see that latch is closed and the safety pin is in position. Check to see that the
trailer will not come off ball by lifting trailer with trailer jack. Balls and hitches wear and should
be replaced when slack shows.
2. Electrical connectors: “pig-tail” is connected to tow vehicle.
3. All lights are working properly.
4. Brakes are working properly. Move trailer slowly and depress tow vehicle foot pedal to see that
trailer brakes lock.
5. Inspect tires for wear. Check tire pressure. Inflate tire to 65 PSI. Under inflated tires run hot and
may blowout.
When connecting the trailer to truck, extreme care should be taken to prevent running into the trailer hitch
and jolting it hard as this will cause the plunger that goes into the master cylinder to bend and bind
causing the master cylinder to stick and not completely release brakes. This will cause the brake shoes to
wear and heat. The heat can cause a tire to blow-out and ruin both tire, brake and drum.