HET 4 DRIVELINE Flashcards
DRIVELINE FUNDAMENTALS AND SERVICE 190401b
Why is correct phasing of a driveline important?
Vibration free driveline
What tool is used to check for phasing?
inclinometer or bubble level
How accurate are inclinometers?
1/4 degree
What is the minimum degree needed for lubrication in a driveline?
1°
What is the preferred angle for lubrication of the driveline?
high driveline angle
When taking a bubble level scale reading from one u-joint yoke to the next, what condition is the driveline in if the readings are not 0 on both?
Tube could be twisted
Slip joint assembled incorrectly
What do the readings on the bubble scale level mean if they are zero on both universal joint yokes on the driveline?
Driveline is in PHASE
If the slip joint is installed 180° out of alignment, what would the phasing and balance be of the driveline?
Phasing would look correct but the balance would be out
If a driveshaft is angled down what type of degree does it have? (positive, zero or negative)
Positive dregree
If a driveshaft is level what degree does it have?
positive, zero or negative
Zero degree
Where should your inclinometer be placed when checking for phasing?
on a machined surface
the yoke is usually cast and might not be a good surface to take a reading from
When taking a reading on the driveline with a bubble level gauge, is it okay to move it any which way while switching which u-joint is being measured?
NO, same direction same way from each point
Why is driveline phase and yokes being parallel to each other important?
so no vibration is created and u-joints are able to spread lube
When measuring driveline, at what end of the vehicle should you start at?
the front of the vehicle (transmission output shaft)
If both readings of the angle of the driveshaft u-joint are positive, what should be done to the reading to find the working angle?
Subtract them from eachother
If one shaft u-joint slopes up and the other slopes down, what must be done to the angles to find the working angle?
Add them together
When are multiple drive shafts used?
Tandem Rear Axle
Long wheel base
Aux transmission - more gear selections
True or False?
Seals can handle and support the weight of the driveshaft?
FALSE
What should be done with exposed driveshafts, above the frame of the vehicle, in regards to safety?
Guards, shields
On a long single driveshaft what should be used to help support the load?
Midship bearing, steady bearing or center support
On what type of vehicles are single driveshafts used on?
Short-wheel based vehicles
Midship bearings are generally sealed or serviceable?
Sealed
What is the purpose of a slip joint on a driveshaft?
To handle change in length, caused by suspension travel
What is the basic purpose of the drivetrain?
To transmit power from the Drive member to the Driven member
What dictates the allowable limits in a drivetrain?
Manufacture spec, service manual
What can cause damage to the driveline tube?
Impacts from terrain, overloaded, high torque load
A bent/damaged driveline tube can be cause what symptom?
Vibration
To true the balance of a driveshaft what can be done?
Weights can be added to balance the driveshaft
Is it every allowable to have a driveshaft out by one tooth, in regards to phase?
Yes, engineered design - heavy torque loads
Is runout important on a driveline?
Yes, there very specific allowances for runout
Is the driveline balanced with or without both universal joins?
With u-joints
How are balancing weights mounted to the driveline?
Welded on
Why do drivelines have speed ratings?
The max speed rating is what the driveline has been trued to on special machines
Describe a trunnion on a u-joint?
Highly polished bearing surface, located at the end of each u-joint cross arm
What is required on the bearing strap retaining fasteners?
Locking compound - manufacture spec
What is inside the bearing cap of a u-joint?
Specific number of precision-ground needle bearings
Why is greasing all four bearings caps/trunnions important on a driveline u-joints?
If any bearing cap is not receiving grease will fail prematurely
The small amount of play between internal and external splines on a driveline are for what?
To allow grease/lube to get in between them
If a driveline is well lubes and the slip joint has play up and down AND side to side, what condition is the slip joint in?
Failed, worn out
If a slip joint is worn out what could be the operators complaint?
Vibration
What are the three versions of Yokes?
Half round
Full round
Wing style
What kind of fit should the cap and yoke bore have?
Interference fit
What is most likely to be used with a centre support bearing?
Shims
What is the maximum difference allowed in a parallel shaft arrangement?
1°
What is the other name for a broken-back driveline arrangement?
intersecting angle
What should be done before a visual inspection of driveline components?
Clean the area
What types of damage can be seen on the splines of a split joint?
Twisted
Galling
Excessive movement/play
A slip joint has too much play in the splines, what would be the complaint?
Vibration
If a slip join has too much clearance in the splines what may have a premature failure?
U-joints
What are some signs of lack of lubrication in a driveline?
False brinelling
Rust
Galling
What can cause pitting in a u-joint?
Contaminated lubricant
How should yoke bores and u-joint bearing surfaces be cleaned?
fine emery cloth
What should technicians be aware of when removing u-joints?
The caps will become loose once the cross is removed, secure the caps to the trunnions
Should u-joints be greased before or after install?
After
Why is it important to install u-joints the correct way, with a press?
Brinelling can be caused by a bad install
Driveline vibrations can be caused by a multitude of problems, what are some questions that should be asked before trying to find the fault?
When did the vibration start?
Was it gradual or sudden?
Were you loaded or empty?
What were the road conditions?
At what speed and RPM did it occur?
Did it happen during acceleration or deceleration?
Has the suspension or wheel base changed recently?
What are the 5 steps to diagnose a driveline vibration?
Gather Info Road Test Simulate Conditions Record Findings Stationary Inspection
Who is the best person to check for the balance of a driveshaft?
A specialized driveshaft shop
Stationary test of driveline are done in what position in the transmission?
Neutral
What speeds should be gone through in a stationary test?
Idle to governed speed
If a vehicle has a long wheelbase and multiple driveshafts, do you have to use midship bearings or is there another way to support the system?
To NOT use midship bearings, there would have to be multiple rear axles and/or auxiliary transmission, it would shorted then shafts helping with the weight
For on-road application what is generally the largest allowable working angle in the drivetrain?
3°
A brokeback drivetrain system has a positive angle of 3° at one end and a negative angle of 3° at the other end, what is the result?
They zero each other out
What are the two ways to secure a yoke to a driveshaft tube?
Welded or slip (sleeve) that spline to the stub tube
What are the arrows on a different parts of the driveline for?
To align the driveshaft - proper phasing
How are the ends of a driveshaft tube mounted (stub shaft or tube yoke)?
Welded
What does Air Ride Suspension do to our driveline angles?
Tries to keep the angle constant
If a vehicle does not have air ride suspension, what could happen to the driveline angles as the vehicle is loaded and unloaded?
Angles will change with weight
When removing drivelines, you should always follow all safety precautions. What should a technician be aware of when removing a driveline?
Non-destructive marking for alignment
What types of u-joints eliminate pulsation in the driveshaft?
CV, double cardan, double universal
What is the first visual indication of worn u-joints?
RUST
What is used to connect a driveline at two components?
2 universal joints - parallel
What type of driveline yokes are most commonly used in heavy equipment (off-road)?
Wing type
What type of driveline yokes are used in heavy truck (on-road)?
Full or Half round yokes
What can cause universal trunnions to have end galling?
Lack of lube or high working angle
What attaches two yokes together?
U joints
Why are alignment marks important on drivelines?
Manufacture spec may have the driveline out of phase
How many bearing caps mount to a yoke?
2
