LETP Week 1 Monday

What type of forces are involved when the couplers of a train are stretched?
Draft forces

What type of service brake application is activated by a safety device?
Penalty brake application

What is the term that describes the difference in brake pipe pressure between the locomotive (source of supply) and the rear car?
Brake pipe gradient

Referring to brake pipe gradient, what term is used to describe the condition that exists when the system is less than fully charged?
False gradient

Referring to brake pipe gradient, what term is used to describe the temporary condition that exists when the brake pipe pressure is higher at the rear of the train than at the head end?
Inverse gradient

Referring to brake pipe gradient, what term is used to describe the condition that exists when the system is fully charged?
Normal gradient

What forces are involved when the couplers in a train are compressed (slack-bunched)?
Buff forces

What is the term that describes movement of part of a coupled train at a speed different from another part of the train?
Slack action

What is the term that describes a service reduction of brake pipe pressure that equalizes the pressure between the brake cylinder and the auxiliary reservoir?
Full service application

What is the action required to prevent an automatic brake application on the locomotive(s) or to release the locomotive brakes from an automatic brake application?
Actuating

What is the valve that reduces air pressure from the locomotive main reservoir to the desired pressure in the brake pipe?
Regulating valve

What device is used to cut in or cut out the automatic brake valve?
Brake valve cut off valve

What valve is used to cut in or cut out the independent brake valve?
MU cutout cock, MU-2-A, or Dual-ported cutout cock (all the same)

Definition of light grade?
Grade less than 1.0%

Definition of heavy grade?
Grade at least 1.0% for a distance of 3 miles or more

Definition of mountain grade?
2.0% grade or greater for a distance of 2 miles or more

What is the device found on locomotives and cars that charges reservoirs and applies or releases brake cylinder pressure in response to changes in brake pipe pressure?
Control valve

What is the brake that controls the locomotive brakes independent of the ABV handle position?
Independent brake valve

Making an “over reduction” decreases _____________ pressure without increasing ____________ pressure.
Brake pipe pressure, brake cylinder

How much retarding force per axle does a high capacity dynamic brake provide?
13500 lbs

What is the instrument that measures the air flow through the automatic brake valve to the brake pipe?
Air flow indicator

What is dynamic brake?
An electrical device that converts some of the energy developed by a moving locomotive into an effective retarding force.

What is a “slug?”
A unit with traction motors but no diesel engine and incapable of propelling itself. The unit receives electrical power through a power cable from an adjacent, specially equipped locomotive. Slugs are used where low speeds and high tractive effort are needed.

What is the term for cracks in railroad wheels normally caused by the heat generated on the tread and flange of the wheel from excessive braking?
Thermal cracks

What is the term for adjusting the throttle one notch at a time to control train speed and in-train forces without applying air brakes?
Throttle modulation

What is the name of the air-operated, electrical switch activated by an emergency or penalty brake application?
Pneumatic control switch (PCS)

What effect does activation of the PCS switch have?
Drops that engine speed to idle on EMD locos or throttle notch 1 on GE locomotives.

What are specially equipped couplers that only allow coupler buff to move laterally within certain limits and minimize rail turnover, wheel climb, and jackknifing?
Alignment control coupler

What is normal gradient?
The gradient that exists when the system is fully charged

What determines if a service or emergency brake application occurs?
The rate that the air drops

What is an auxiliary reservoir?
A storage volume, charged from the brake pipe, to receive and store air to apply brakes on a car or locomotive in freight car equipment. The auxiliary reservoir and emergency reservoir are combined in one structure.

What is an emergency reservoir?
A storage volume, charged from the brake pipe, to receive and store air used during emergency brake applications and certain recharge features.

What is a service application?
When brake pipe pressure exhausts at a service rate to apply the train brakes.

Define automatic brake valve handle position “release”
Charges the brake pipe to the regulating valve setting (90 psi for freight) and releases the locomotive and train brakes.

Define automatic brake valve handle position “minimum reduction”
Reduces equalizing reservoir and brake pipe pressure 6-8 psi

Define automatic brake valve handle position “service zone”
Gradually reduces equalizing reservoir and brake pipe pressures in increasing amounts as the brake handle is moved to the right. Moving the brake handle to the left with the brake valve cutout valve in PASS will increase equalizing reservoir and brake pipe pressure. Use extreme care when operating freight trains with automatic brake valve cutout valve in PASS.

Define automatic brake valve handle position “full service”
Reduces equalizing pressure and brake pipe pressure to near equalization.

Define automatic brake valve handle position “suppression”
Restores control of the locomotive after a safety control (penalty) brake application. To recover control, leave the brake handle in this position for 60 seconds.

Define automatic brake valve handle position “handle off/continuous service”
Reduces equalizing reservoir and brake pipe pressure at a service rate. Use this handle position for trailing locomotives and locomotives hauled dead-in-train.

Define automatic brake valve handle position “emergency”
Vents brake pipe pressure directly to the atmosphere, causing brakes to apply at an emergency rate.

What is the definition of TOB and what is the formula to figure it?
Gross trailing tonnage of the train divided by the total number of cars having operative brakes. No locomotive weight is included.

What is the formula for figuring HPT?
Total horsepower of all WORKING locomotives divided by total trailing weight of train and isolated locomotives in tons.

When figuring TODB what is used in the formula and are isolated engines used in this equation?
Total gross trailing tonnage of train divided by the number of axles of locomotives, including helpers, operating in dynamic brake. When making this calculation, include in the gross trailing tonnage the weight of any locomotive, including a helper locomotive, not operating in dynamic brake or with dynamic brake cut out. Refer to locomotive data tables in system special instructions for dynamic brake axle ratings.

What does it mean when brake equipment if overcharged?
Brake equipment charged to higher pressure than the regulating valve is adjusted for or can maintain. In such a condition, brakes on a portion of the train may not release.

What is the difference between a Flat (grid control) dynamic brake system and a Taper dynamic (speed control) brake system?
Flat dynamic brake system provides retardation that is controlled by the position of the dynamic brake lever. Maximum retardation occurs at position 8.

Taper dynamic brake system provided retardation relative to both speed and dynamic brake handle position. The higher the speed the greater the retarding force developed for a given handle position. At higher speeds, full dynamic brake effort is reached at position 4.

What is accelerometer?
An indicator that displays in MPH per minute the rate of increase or decrease of speed.

What is air compressor?
A locomotive device, powered by the diesel engine or an electric motor, that compresses air for operating the air brakes and all other air-operated devices on locomotives and cars.

What is ampere (amperage, Amps)
The standard unit for measuring electric current.

Define balance braking.
Controlling train speed by making enough of a brake pipe reduction to stabilize speed on a grade, then allowing the automatic brake valve pressure maintaining feature to hold the brake application constant regardless of brake pipe leakage. this ordinarily is accomplished in combination with dynamic braking.

Define Bleed (Bleed-off)
Venting air pressure to the atmosphere, such as venting air pressure from the brake cylinder of individual cars by using the release valve.

Define brake application.
The rate at which air leaves the system. A brake pipe pressure reduction (no matter how made) that causes the control or distributing valve to move to the service or emergency position.

Define Brake pipe (Little brother)
The section of air brake piping of a car or locomotive that supplies the reservoirs. It also connects the piping to allow the locomotive engineer to control the car brakes. The pipe is 1-1/4 inches in diameter and extends from one end of the car to the other. At the ends, flexible hoses connect the cars. When a train is made up and all brake pipes on the cars are joined together, the entire pipe line is called the brake pipe.

Define control valve (brains of braking system)
A device on locomotives or cars that charges the reservoirs and applies or releases brake cylinder pressure when brake pipe pressure reduces or increases

Disturbed track
A section of passable track that has a temporary speed restriction imposed because various defects or track maintenance has affected the integrity of the track.

What is dynamic brake holding feature?
A feature of the lead, controlling locomotive that allows dynamic braking effort when a PCS open condition exists. Only works if have 14 lbs. or less independent brake set.

Define equalizing reservoir (Big brother)
A small reservoir connected to a piston or diaphragm chamber and used in automatic air brake operations. It is only cut in on the controlling unit. The reservoir’s purpose is to add volume of air to one side of the chamber, which can be accurately controlled. When a brake pipe reduction occurs, air is drawn from the equalizing reservoir. The reservoir then automatically draws the proper amount of air from the brake pipe. For this reason, the brake pipe pressure and the equalizing reservoir pressure are always the same, except when they are equalizing after a brake pipe reduction or a brake pipe charging operation.

End-of-train telemetry devices consist of….
End-of-train device (ETD) mounted on the trailing coupler of the last car; head-of-train device (HTD) mounted in the locomotive.

An ETD that has not been armed to, provides…
Last car brake pipe pressure monitoring; Last car motion status (moving or stopped); Marker light status (on or off); ETD battery status.

An ETD that has been armed to (emergency enabled) provides….
capability to initiate an emergency brake application at the rear of the train. Both the HTD and ETD must be equipped for two-way communication and the HTD must be armed to the ETD (emergency enabled). An emergency toggle switch associated with the HTD cab display is used to activate the ETD emergency valve.

A system of components that determines the rear car brake pipe pressure and transmits that information to the display on the controlling unit.

A 2-way ETD transmits and receives information between the head-end and rear-end units. The additional purpose of a 2-way ETD is to provide a way to initiate from the locomotive an emergency brake application at the rear of the train. For this to happen, both the head-end and the rear-end units must be equipped for two-way communication and armed (emergency enabled). An emergency toggle switch associated with the ETD cab display is used to activate the ETD emergency valve located on the rear-end.

What does an HTD display?
Last car brake pipe pressure; last car motion status (moving or stopped); marker light status (on or off); ETD battery status; communication Status with ETD; 2-way Armed Status; Distance measurement referenced to locomotive movement.

HTD provides…
Audible alarms pertaining to status changes; arming capability to a selected 2-way ETD; Interface for Manual and Automatic initiated ETD emergencies.

Define horsepower per ton….
The total horsepower of all working locomotives divided by the total trailing weight of the train and isolated locomotives in tons. For example, a train powered by 15000 horsepower and a train weight of 4285 tons with two isolated locomotives weighing 400 tons has a 3.2 horsepower per trailing ton ratio (15000 HP divided by 4685 tons).

Define isolation switch
A switch on diesel electric locomotives that has two or three positions. In RUN position, the unit is “on line, ” responds to control, and develops power. In the ISOLATION (or stop-start) position, the unit is isolated from the consist and does not develop power or respond to control.

Define Main reservoir
An air reservoir on the locomotive for storing, cooling, and drying compressed air. Main reservoir pressure is 120-140 psi

Define off air
Off air means when it is known that a brake system has not been connected to a continuous source of compressed air of at least 60 psi for a period of 4 hours or more. The “source” of compressed air is brake pipe pressure being supplied at the locomotive(s) or yard air connection to the brake system. If brake pipe gradient is observed, no minimum brake pipe pressure at the opposite end of a brake system is required as long as 60 psi or more is being maintained at the charging end of the brake system.

Define Overcharge
Brake equipment charged to a higher pressure than the regulating valve is adjusted for or can maintain. In such a condition, brakes on a portion of the train may not release.

What is pressure maintaining braking?
Controlling train speed by making enough of a brake pipe reduction to stabilize speed on a grade, then allowing the automatic brake valve pressure maintaining feature to hold the brake application constant regardless of brake pipe leakage.

Define pressure maintaining feature
A system designed to overcome brake pipe leakage both in the release and service positions of the automatic brake valve. This allows a constant brake application to be held as long as needed.

Define Reduction (of the brake pipe)
A decrease in brake pipe pressure at a rate and of an amount sufficient to cause a train brake application to be initiate or increased.

Define reduction relay valve
A device on long cars that helps brake pipe pressure reduce during service and emergency brake applications. The valve compensates for the added length of brake pipe on long cars (1-2 lb. reduction can change brakes from setting or releasing).

Define regulating valve
The valve that reduces air pressure from the locomotive’s main reservoir to the desired pressure in the brake pipe. The regulating valve will automatically maintain that pressure when the automatic brake valve is in the RELEASE position.

Define transfer train movement
A train that travels between a point of origin and a point of final destination not exceeding 20 miles. Such trains may pick up or deliver freight equipment while en route to destination.

Define Vent valve
A valve attached to the brake system of a car or locomotive. The valve responds to an emergency brake pipe pressure rate of reduction by venting the brake pipe at each vehicle to the atmosphere. As a result, the emergency application spreads throughout the train.

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