190303d Flashcards
What is the purpose of the transmission scavenging pump and the torque converter scavenging pump?
To remove leakage oil from transmission/torque converter therefore removing built up oil that has become hot, preventing over heating.
What is the purpose of the priority valve?
It is to ensure that oil pressure is available for steering clutch and brake functions before transmission functions.
What exactly is a priority valve?
A normally closed pressure control valve.
Why is there an inlet relief valve on a transmission charge system?
This is for cold weather starts until the torque converter oil warms up.
Transmission and hydraulic oil are very similar. What is the difference?
Transmission oils are specifically formulated to provide maximum life of the friction material of the clutch discs.
What is commonly used to control clutch release rates?
An orfice
Controlling the rate of clutch application is often called what?
Clutch modulation
A desirable feature in most heavy equipment applications is the ability to prevent automatic shifting from occurring during certain phases of the machine’s operating cycle.
T/F
True
The three (3) hydraulic circuits in a basic shift control system are:
a) the clutch application circuit
b) the converter charging circuit
c) the transmission lubrication circuit
In a basic hydraulic shift control system, transmission speed and direction changes
are made by the:
shift selector valve.
The function of the clutch pressure regulator valve is to
limit the application pressure
applied to the transmission clutch pistons
The circuit that receives oil flow after the clutch application circuit has been satisfied,
is the:
converter charging circuit.
Maximum oil pressure within the torque converter is controlled by
the torque converter relief valve.
Torque converter outlet oil flow is cooled and filtered before it is directed into the
transmission lubrication circuit.
Some transmissions are equipped with a scavenging pump whose function is to:
remove leakage oil from the transmission case.
The term clutch modulation refers to
controlling the buildup of pressure in the clutch piston allowing controlled slippage of the clutch discs.
Oil flow for transmission control system operation is supplied by
a charging pump
that is driven at engine speed.
The purpose of modulating the application of transmission clutches is to prevent shift shock.
true
The two (2) factors that influence the point at which an automatic transmission will shift are:
a) machine ground speed
b) the operator’s demand for power.
The function of the governor circuit in and automatic transmission is to:
provide a hydraulic signal that is proportional to machine ground speed.
The hydraulic governor in an automatic transmission operates by balancing the
centrifugal force of the governor flyweights against:
governor pressure.