SAFETY MEETING

Off Highway Trucks

Brakes

There are four separate controls used for brakingService BrakeRetarderSecondary BrakeParking Brake

Yellow- Secondary Parking Spring Applied /Oil Released

Purple - Service/ Retarding

Air Over Oil Applied

Dual Piston

Service Brake

For general brakingAids Retarder Front brake switch

On: front and rear wheel brakes

Off: rear wheels only

Not for downhill retarding

RetarderFor long downgrade

brakingRear brakes only =

777 and down (unless 777 is equipped with “wet” front brakes)

All brakes = 785 and upUse service brake to assist Lever stays in position

Secondary Brake

Red Lever / Foot PedalTest when ready to move

Apply secondary brake Release the parking brakePut transmission in 1st gear and

bring rpm to 1200Truck should not move--if it

moves, do not operate

Applies front and rear brakes

Parking Brake

Applies only the rear wheel brakes

Use whenat restloadingdumping

Front Brake Switch (769-777)

Leave in ‘on’ position for emergency use

All brakes apply when service brake used

Use manual retarder or ARC when descending grades

Automatic Retarder Control

More efficient than manual retarding

Leave ‘On’ during normal operation

Will allow transmission to upshift one gear if on or off

It applies brakes to maintain constant rpm

Downgrade Retarding

Watch brake oil temperatureStop and cool brake oilSpeed = Heat

Braking/Retarding - Manual/Auto

ManualSelect proper gear for gradeProper rpm 1700 – 2300 RPM (769D – 775E)

Below 1700 RPM brake oil flow is inadequate. Hold truck at proper RPM unless unsafe.

ARCVerify switch is on.Select proper gear for gradeOperating range – 2160 – 2300 RPM (769D – 775E)

Note: If brake oil temp. climbs quickly, lower the gear.

RETARDER (rule of thumb)

What ever gear you travel up hill empty, you travel one gear LOWER down hill when loaded.

What ever gear you travel uphill loaded, you use one gear higher coming down empty.

What ever gear you travel uphill loaded, come down loaded in the same gear.

Remember HEAT is the guideline, if brakes get hot slow down. Gear down to keep over heating under control

ARC engine over speed protection

If engine approaches an unsafe engine speed ARC will engage the brakes even if the ARC is OFF.

An overspeed condition will occur at 2100 rpm. If the operator ignores this, the ARC will engage at 2180 rpm. If the speed continues to increase, the power train will upshift one gear, or if it is in the top gear, it will engage the torque converter drive at 2300 rpm.

RETARDER

for long downgrade braking

• retarder applies 80% of available pressure, which is easier to modulate than the 100%.

• avoid continuously engaging & disengaging

• observe brake oil temperature

• use service brake to assist

• do not use for PARKING brake!

• select proper gear for downhill

RETARDER

• When do you use retarder vs. service brake?• Down grades

• Load/Dump area

• What factors could affect when to use the retarder or service brake?• Site specific issues.

• Conditions (weather, materials, etc…)

When the air system is drained, the parking brake reset valve will not allow the parking brake to be released until the system is full of air and the operator manually has to push this yellow button down.

Brake Tests When do you conduct them? Start of shift Which ones? Service, Secondary and Park Brakes How? Apply brake being tested, release park brake(unless it

is under test), gradually increase engine speed to approximately 1200 rpm, truck should not move. Do not operate if it does and have necessary repairs made.

Supplemental Steering (769-777)

Check DailyKey in ‘run’ position,

test switch upCheck steeringTest switch down

Secondary Steering Test (785-797)

The engine must be shut off with the emergency shutdown switch while leaving the key start switch on. When this switch is used, the bleed down solenoid is not energized and the accumulators will not allow the oil to go back to the steering tank. The truck can now be tested with the engine stopped.

VIMS monitors the accumulator pressure and refers to this as the, “High Steering Pressure Switch”.

Secondary Steering CheckWhen engine is off and the oil is cold the oil should

be between the FULL and ADD marks of the upper gauge.

Accumulators(primary- secondary) - engine should be running and the level should not be lower than the engine running mark in the lower sight glass. If the oil is low have the nitrogen charge checked in the accumulator. If the charge is low, it could allow excess oil to be stored in the accumulators.

1

2

CHECK WITHENGINE RUNNINGAND OIL IS HOT“FULL”

CHECK WITHENGINE STOPPEDAND OIL IS COLD“FULL”

TCS SwitchFind a clear, level, large area ;shift into

1st gear, low idleTurn steering wheel all the way to the

left/right and drive in a complete circlePress and hold TCS test switch onMachine will stop; outside brakes will

releaseRelease test switch Repeat test while moving the other

direction

Brake Release Switch

Brake release switch- parking brake off, engine start switch to on, brake release switch to the on position hold until VIMS indicates the parking brake is released.

FYI can be used for lower the bed with dead engine;

1. Start switch to on

2. Hoist to body down position

3. Hold brake release for 20 sec

4. If it does not go down, hold hoist in raise position for 15 seconds. Move hoist to lower, if it still does not go down, there is a problem!

Truck Payload Management System

• Payload Operator Display

• May be part of VIMS

• Load Indicator Lights

• Green = keep loading

• Flashing red = last pass

• Red = truck is full• ‘ON/OFF’ switch

• Test Switch

• Also tracks:

• total weight hauled

• total loads

THANK

YOU