ASE P1 Medium-Heavy Truck Parts Specialist flashcards

37 cards. Read the term and the definition here. The deck at the top of this page is optional.

Reorder point formula

Reorder point = (average daily demand × lead time in days) + safety stock. It signals when to place a new order to avoid stockouts.

Economic order quantity (EOQ)

EOQ = √(2DS/H), where D is annual demand, S is order cost, and H is holding cost per unit per year. It minimizes total inventory costs.

ABC inventory classification

A method that categorizes inventory by value and turnover: A items are high-value/low-count, B moderate, and C low-value/high-count, guiding management focus.

Cycle counting

A system of counting a subset of inventory items on a rotating schedule to verify accuracy and identify discrepancies without a full physical inventory.

VIN check digit

The ninth character of a VIN, calculated from the other characters, used to verify the VIN's validity and detect transcription errors.

VIN model year code

The tenth character of a VIN indicates model year: 2010=A, 2011=B, 2012=C, 2013=D, 2014=E, 2015=F, 2016=G, 2017=H, 2018=J, 2019=K, 2020=L, 2021=M, 2022=N, 2023=P, 2024=R, 2025=S.

Part supersession

A manufacturer's replacement of an old part number with a new one that is backward-compatible, often due to design changes or supplier updates.

ACES and PIES standards

ACES defines vehicle application data; PIES defines product information for aftermarket electronic catalogs, enabling accurate parts lookup and interchange.

Diesel compression ratio

The ratio of cylinder volume at bottom dead center to volume at top dead center; diesel engines typically use 16:1 to 22:1 to achieve ignition by compression heat.

Common rail fuel system

A diesel fuel injection system where a high-pressure pump supplies fuel to a common accumulator (rail), and electronically controlled injectors deliver fuel to each cylinder.

EGR system function

Exhaust gas recirculation routes a portion of exhaust back into the intake to lower combustion temperature and reduce nitrogen oxide (NOx) emissions.

DPF regeneration

The process of burning off accumulated soot in a diesel particulate filter, either passively through exhaust heat or actively via post-injection and elevated temperature.

Overall drive ratio

The product of the transmission gear ratio and the axle ratio; used to calculate engine speed relative to vehicle speed and to match powertrain to load.

Differential gear ratio

The number of teeth on the ring gear divided by the number of teeth on the pinion gear; determines torque multiplication and speed relationship between driveshaft and wheels.

Limited-slip differential

A differential that limits wheel spin by transferring torque to the wheel with traction, using clutch packs or gear mechanisms, and often requires friction-modified lubricant.

Driveshaft phasing

The alignment of universal joint yokes so that their ears are in the same plane, minimizing vibration and ensuring smooth power transmission.

DOT brake fluid types

DOT 3, DOT 4, and DOT 5.1 are glycol-based and hygroscopic; DOT 5 is silicone-based and not compatible with glycol fluids. Use only the specified type.

Slack adjuster function

A component in air brake systems that adjusts the pushrod stroke to compensate for brake shoe wear, maintaining proper braking force and response.

Spring brake operation

A parking/emergency brake mechanism that uses a powerful spring to apply the brakes when air pressure is released, ensuring brakes engage if air pressure is lost.

ABS wheel speed sensor

A sensor that monitors wheel rotation speed and sends a signal to the ABS control module; a damaged tone ring or incorrect air gap can cause fault codes.

Ackermann steering geometry

A steering linkage design where the inner wheel turns at a sharper angle than the outer wheel, reducing tire scrub and improving handling during turns.

Caster angle

The forward or rearward tilt of the steering axis relative to vertical; positive caster improves straight-line stability and steering return.

Camber angle

The inward or outward tilt of the top of the wheel relative to vertical; negative camber tilts the top inward, affecting tire wear and cornering.

Kingpin inclination (KPI)

The angle between the kingpin axis and vertical, viewed from the front; it affects steering effort and returnability.

Ohm's law

V = I × R, where V is voltage, I is current, and R is resistance; power can be calculated as P = V × I = I²R = V²/R.

Series circuit rules

Total resistance equals the sum of individual resistances; current is the same through all components; voltage divides across components.

Parallel circuit rules

Total resistance is less than the smallest individual resistance; voltage is the same across all branches; current divides among branches.

Battery CCA rating

Cold cranking amps indicates the current a battery can deliver at 0°F (-18°C) for 30 seconds while maintaining at least 7.2 volts, reflecting starting capability.

Coolant mixture ratio

A 50/50 mix of antifreeze and water provides freeze protection to about -34°F (-37°C) and raises the boiling point, suitable for most conditions.

Supplemental coolant additives (SCAs)

Chemicals added to diesel engine coolant to prevent liner cavitation and corrosion; required for conventional coolants, while OAT coolants may not need them.

API diesel oil categories

API service categories such as CJ-4 and CK-4 denote oil performance for diesel engines; CK-4 is backward-compatible and offers improved oxidation resistance.

A/C system pressures

Typical low-side pressure is 25–45 psi and high-side is 150–250 psi, varying with ambient temperature; abnormal readings indicate system faults.

Heater core function

A small radiator inside the HVAC box that uses engine coolant to warm air for cabin heating; leaks can cause coolant loss and windshield fogging.

Blend door actuator

An electric or vacuum motor that moves a door to mix hot and cold air, controlling cabin temperature; failure results in temperature control problems.

Core charge

A refundable deposit added to the price of a rebuilt part, returned when the old core is returned in acceptable condition for remanufacturing.

Return authorization (RA)

A number issued by the seller permitting a customer to return parts; it helps track returns and ensures proper credit or replacement.

Restocking fee

A percentage (often 10–25%) deducted from a refund for returned parts that are not defective, covering handling and repackaging costs.