HET 4 TRANSMISSION Flashcards
What are the three basic functions of a transmission?
Multiply Torque
Reverse
Neutral
What are the classifications of transmissions?
Synchronized or non-synchronized Single or Multiple Countershafts Number of forward ratios/gears Final Gear ratio - overdrive or direct Manual or automated shift
If you need to find a gear ratio through multiple gear pairs, what needs to be done to the ratios?
Multiple
Input torque is 1000ft/lb, gear ratio is 2:1, what is the output torque?
2000ft/lb
What is the formula to find output speed if given input speed and a gear ratio?
Input Speed ÷ Gear Ratio = RPM
What two things does a technician need to find out everything about a manufactures transmission?
Model number and spec sheet
What are two things that should be considered before picking a transmission for a vehicle?
Horsepower and torque curves
If a transmission has a 35% ratio step between gears, does it have a smaller or larger ratio change between each gear as compared to a 20% ratio step?
Larger ratio changes
What are some transmission components?
Transmission input shaft and drive gear main shaft and gears synchronizers shift lever shift rail and forks detents interlocked
Transmission input shaft is also called?
Clutch shaft
Constant mesh means?
when Input turns = all gears are turning
What are the other names for a transmission input shaft gear?
Transmission drive gear
Main drive gear
Is neutral a gear position?
No
How many gear ratios does a transmission use at the same time (USUALLY)?
2 gear ratios
Operator Complaint: Apply clutch pedal to shift and its hard to shift, grinding gears. What could be the fault?
Seized Pilot Bearing
If a pilot bearing is seized what will happen when the clutch pedal is depressed?
No break in path of power, shaft continues to spin, cannot shift
Why is end play important?
Allows for expansion
Transmissions should be running at what temperature?
About 100°F above ambient temp
Does the countershaft or mainshaft need more thrust washers?
Mainshaft needs more
What type of bearings are used to support the mainshaft?
Anti-Friction bearings
How many of the mainshaft gears are connected to the main shaft?
None
pg 14 190401dA
What is the main purpose of the thrust washers? (wear)
Reduce gear wear
How many gears are attached to the input shaft?
One - Drive input gear
What are some ways to stop a thrust washer from turning?
Tabs, Tangs, Snap Rings
What type of teeth are on the side of a transmission gear?
Dog Teeth
A blocker ring is usually made of what material?
Brass/Bronze
What is the function of the insert in a synchronizer hub?
- Holds shift collar in centered position (neutral)
2. Allow blocker ring to line up the two gears, before joining together
True or False:
The inserts in the blocker ring are a tight fit?
False
How are the inserts in the synchronizer hub held out?
Spring force
What is the purpose of the groves cut into the baulk ring?
To cut through the oil film
What are the 3 stages/phases of synchronizing?
- Braking/Energizing
- Synchronization - same RPM
- Engagement
Operator complains about grinding gears when shifting quickly. What could be the fault?
Damaged/Failed synchronizer
What is used on some pin type synchronizers to provide spring-loaded resistance?
Split pins
In a plate and disc synchronizer, where do the reaction discs spline and where do the friction discs spline?
Friction Disc - Blocker assembly Reaction Disc (plate) - Synchronizer drum
Three types of synchronized types?
Blocker
Pin Type
Plate and Disc synchronizer
In neutral position are the plates and discs synchronizers slipping or engaging with each other?
Slipping
How many pieces is a shift level (usually)?
two piece
What is the purpose of a spade pin in a shift level assembly?
To stop lever from rotating
What usually sits over top of the shift lever housing?
Protective boot
Operator complains that shifting is becoming difficult. The technician finds the boot is torn on the shift lever assembly, what could be the fault?
Contamination around moving parts in the lower lever
When could a shift lever slip out from gear?
During Acceleration or Deceleration
When could a shift lever Jump out from a worn detente grove?
When torque load is applied
Where is the reverse light switch located on a transmission?
On the shift bar housing
If a transmission breather clogs, what could be a result?
Input/Output seals fail - leak
Shift fork can also be called?
Shift yoke
Shift bars can also be called?
Yoke bars
What would be the purpose of a spring-loaded plunger on the first/reverse shift block?
Lock out device so operator does not select 1st or reverse at high speed
What is the purpose of an interlock?
To prevent operator from selecting more than one gear at once
Where is an interlock located?
in the shift rails
When is the torque from the engine split evenly between two countershafts?
When the shafts are positioned 180° apart
What dictates a floating mainshaft?
The floating mainshaft has no bearings between the mainshaft and mainshaft gears
It floats between two countershafts
What is an advantage of a multiple countershaft transmission?
smaller, lighter
With multiple countershafts, what type of gears can be used?
Smaller gears, spur gears can be used, no thrust washers
Why were remote auxiliary transmissions a bad idea when they had shift linkages?
susceptible to wear and damaged from falling objects
Air shift auxiliary transmissions were preferred to remote aux transmissions, why?
Less likely to have shift problems due to damaged or dirty mechanical linkage
Why is important to drain air tanks daily on a truck with an air shift auxiliary transmissions?
The small air lines are susceptible to water
With multiple countershafts, what could be done to the housing of the transmissions?
Lighter, Aluminum - better heat dispersion
How is alignment held in a multiple countershaft transmission?
Precise doweling
What are the biggest causes of failures in a transmissions?
Contamination - usually from servicing
Oil return threads are also called?
Wind back seal
What stops oil from leaking out of the transmission?
Wind back seal(reverse thread) and gasket under the cover
On a multiple countershaft transmission, all the gears are the same size on the opposite shaft, except which ones?
PTO gears
Where are the timing marks usually found on multiple counter shaft transmissions?
On the countershaft gears
What is the usual position of the transmission to remove the gearshift cover?
Normally Neutral
*Ford may require transmission to be in Reverse
Jump out and Slip out cause the transmission to go into what position?
Neutral
Jump out can be caused by worn detents or?
Long shifter
Slip out can be caused by worn detents, worn linkage or?
Clutching teeth are worn out or a worn fork/collar
What are the two types of gear teeth on sliding clutches?
Dove tail or straight cut
What gears usually use a dove tail gear tooth on the sliding clutch?
4th and 5th
Do auxiliary transmissions use helical cut gears or straight cut gear?
Helical gears to handle torque
Operator complains of a whine/squeal, what could be the cause?
Insufficient clearances
PTO w/out backlash
mix matched gears
What could cause a transmission to get stuck in gear?
twisted mainshaft worn shift tower housing worn input shaft splines misadjusted clutch/clutch brake counter shaft brake
What are some things that should be visually inspected when there is a transmission fault?
Engine and Transmission mounts
Clutch system condition
driveline condition
shift mechanism operation
If an operator regularly coasts down hill with the clutch pedal depressed, what could be the fault they are causing?
Over heating
True or False
A vehicle being driven under 32km/h constantly will have no faults?
False - unless adequate coolers are used
What are three things that can cause a transmission to growl?
Broken gear teeth
Incorrect timing - will show up immediately after rebuild
Bad Bearings
What type of bearing(s) support a mainshaft?
1 friction and 1 anti-friction
What causes spalling on transmission gear teeth?
Overloading over a short period of time
What can cause gear clash?
Improperly adjusted clutch
damaged clutch brake
seized pilot bearing
damaged splines on shaft
A gear rattle can be cause by?
A rough running engine
True or False.
Frosted gears should be replaced immediately?
False - normal wear
True or False
Initial pitting is mild, usually 0.030” depth?
True
Auxiliary section can have how many speed options?
2,3 or 4 speed
On a non-selective mainshaft, what type of washers are used?
non-selective center and outer washers
On a selective gear design mainshaft what type of washers are used?
Non-selective inner washers
Selective outer washers
What is used to measure clearance between gears on a selective mainshaft?
feeler blades
Where would a selective washer be found on a NON-selective mainshaft assembly?
For reverse gear
How many groves are on a selective mainshaft?
3 groves
Chassis air supply pressure is at a minimum of?
90 PSI
What is the final check on a transmission overhaul?
Road test - Leak check
A green or blue plugs might be an indication of what in the transmission?
Synthetic oil
After refiling a transmission with oil, when should oil level be rechecked?
After letting the engine run for a short period to fill the cooler and after the road test
How large should a buffer zone be around a diesel electric hybrid?
1 m all around
Who can repair hybrid vehicles?
Trained/certified personnel
A “00” glove class is good to what voltage rating?
0.5kV
A “4” glove class is good to what voltage rating?
36.0kV
What must be worn over insulated rubber gloves when working with high voltage?
Leather protectors
How often should protective gloves be checked?
Every use
What air pressure is needed to activate the splitter cylinder?
58-63 PSI
Upstream from the air filter/regulator, what should air pressure be (minimum)?
90 PSI
How low does the voltage need to be before working on High voltage system?
Below 30 volts
How is gas charge from an accumulator vented?
Connect a proper venting tool
How many groves are on a non-selective main shaft?
3 groves
An auxiliary transmission is shifted mechanically or with air?
Air
If a 5 speed transmission has a 2 range auxiliary how many speeds are available?
10 speed
Why is a transmission with 20 gears usually called an 18 speed?
Most operators don’t use the lowest two gears
The larger air switch on a gear shift is used to shift what?
Range
The smaller air switch on the gear shift is used to switch?
Spliiter
What should be used when heating bearings to find the correct temperature?
Temp pen - wax
How much ratio change is created with a splitter?
15-20%
A deep reduction gives what in the starting gear?
A lower than normal starting gear
A force lube ring can also be called?
A halo tube
Why are lithium batteries preferred in hybrids?
They can handle constant drain and fill
What does a reduced duty cycle do?
Saves on fuel, better fuel economy
How is output torque calculated?
Input torque x final gear ratio
What is the purpose of a bevel on a sliding clutch?
To ease the engagement process and reduce gear clash during engagement
If a cooler is forced to go over relief, what is created?
Heat
What type of oil coolers are used on transmissions?
Oil to Coolant
On an integral oil pump in a transmission what type of filters are used?
Screen - Magnets in case
How are hybrid vehicles classified?
Mild hybrids and full hybrids
What do mild hybrids not do for a vehicle?
Propel the vehicle without an input from the engine
What does a full hybrid vehicle do for the vehicle?
Take off assist, acceleration, propel the vehicle
What are the two types of hybrid architectures?
Series and Parallel
True or False
In a series hybrid the engine never directly powers the vehicle?
True
In an AC or DC drive electric haul truck what is the common hybrid application?
(Series) Diesel electric - engine powers a generator, that supplies power to a battery that powers wheel motors
What is a common commercial truck hybrid?
Diesel electric parallel hybrid
The electric components of a hybrid include (3)?
Motor/Generator
Inverter
Power Electronics Carrier PEC
What type of motor/generator is used in a diesel parallel electric hybrid?
Brushless permanent magnet induction motor
What is it called when generator charges the batteries?
Regenerative braking
How many phases does the ac power need to be to operate the motor?
Three-phase
What are the three ways hybrids can be propelled?
Electric only
Diesel electric
Diesel only
What is the diesel engine doing while the hybrid is using electric only mode?
Idling
True or False
Diesel electric mode is “parallel”?
True
True/False
During highway cruise speed, the generator recharges the batteries?
False
When are the batteries charged on a diesel electric hybrid?
During braking or coasting
What components are apart of a hydraulic launch assist?
Transfer Case
Hydraulic Pump
Accumulators
Reservoir
At what speed will the hydraulic launch assist disengage?
Vehicle speed exceeds 40 km/h
A vehicle with HLA: the operator wants to coast. What must an operator due to bypass the HLA assist in slowing the vehicle?
Slightly depress the accelerator 10%
What colour are high voltage cables?
Orange
In a four speed aux section, high range and high splitter provide what type of drive?
Direct Drive
What is a synchronizer used for in an aux section of the transmission?
For range shift
Block synchronizers are used on what type of vehicle?
Light duty - automotive
Slip out into neutral can happen when what teeth are worn?
Clutching teeth
What could cause slow/no shifts?
Hydraulic lock on range shifter
Deep reduction can also be called?
Low-low
What are the speed sensors on an automated transmission used for?
The help synchronize shifts
What is the purpose of a start enable relay?
Automated transmission, verifies trans is in netural
When “D, Drive” is selected what gear is the transmission going to begin operation in?
Default
Describe torque locked gears?
Too much torque between the sliding clutches and the gears for the gear motor to move the shift collar to the neutral position
The gear shift knob is called what in a transmission with an auxiliary?
Master air control valve
How many clutches are in the auxiliary two speed?
One sliding clutch
In a semi-automated transmission, what gears become auto?
18th HI and LO
How many clutches are in a auxiliary four speed?
Two sliding clutches
The top 2 solenoid valve is connected to what components?
Splitter cylinder
Air regulator
Range cylinder
A splitter cylinder is exhausting constantly, what could be the fault?
Cylinder seals have failed
Where does air from the air regulator go to?
Splitter cylinder and Range cylinder
Why would suppliers give a silicon based lubricant in a seal kit?
Petroleum products could swell the seals
If a slave cylinder is continuously exhausting air where could the fault be?
Range cylinder
What is the normal position of the splitter?
LOW
What keeps the actuating pin in place?
Spring pressure
Where is the slave valve mounted?
On the transmission, inline with the shift cover
A 15 speed in low range can be split?
Yes
In a 13 speed what is the interlock in the master air control?
In LOW range the transmission cannot be split
The medallion on the top of a shift knob can show a logo or?
A shift pattern
If the regulator does not bring the air pressure down to 58-63 PSI, what needs to be done?
Replace regulator
Does a filter become more or less efficient as it becomes more clogged?
More efficient
A gear shift knob has a blue splitter switch, how many gears does the transmission have?
15 speed
As a truck goes faster, should the gear ratios get smaller or larger?
Smaller closer to direct drive or overdrive
Do plastic air lines or rubber coated cloth braid have a larger or small ID?
Rubber coated cloth braid has a larger ID compared to plastic air lines
When can the actuating pin in the shift cover move?
When the trans is in neutral
What are the two types of airlines used?
Plastic and rubber coated cloth braid
If the range selector is moved UP, what range is selected?
High range
How much of a gear ratio will the Range change?
30-40%
The splitter gives a small gear ration change than the range, what change in percentage is normal?
15-20%
What is the PSI from the air regulator on the transmission?
58-63PSI
An XY shifter has how many motors?
2
A supply air line is normally what colour?
Red
What are airlines connected with?
Brass ferrules/inserts
Is the master air control valve specific to each transmission?
Yes
Is the range cylinder double acting or single acting?
Double acting cylinder
True or False
The range cylinder is double acting and held in position with spring pressure?
False
How is heat reduced in an ECM with a plastic case?
Smaller components that produces less heat
The transmission gear selector motor is what type of motor?
Reversible DC motor
What sensors are on the transmission gear selector motor and gear shifter assembly?
Gear position Sensor
Rail position Sensor
What is the rail position sensor looking for?
Position of the shift finger
When the power is OFF what position are the two solenoids in, in the range and splitter solenoid valve assembly?
Solenoids are moved back with spring pressure allowing cylinders to exhaust
As a range and splitter solenoid valve assembly works, the operator complains the valve is exhausting whenever a shift is made, what is the fault
No fault. small burst of exhaust are normal
Does a solenoid in the range and splitter solenoid valve assembly need to be energized or de-energized to allow air to go to a cylinder?
Energized (one at a time only)
How many speeds sensors are used on a automated shift transmission?
3 sensors
How is an inertia brake controlled?
Electrically
Where is an inertia brake installed?
Transmission power takeoff opening
What does HOLD position allow the operator to do?
manual control over gear changes
In an automated shifting transmission, should the vehicle be allowed to coast in the neutral position?
NO, truck could gain too much speed for the electronic control system to handle
The automated shift transmissions are using what type of data link?
J 1939
At what speed does a J1939 communicate at?
250Kb/s
