Red Seal Agricultural Equipment Technician flashcards

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

Lockout tagout verification

After isolating and locking all energy sources, the technician must attempt a start or test for zero energy to confirm isolation before beginning repair work.

ROPS with seat belt

A rollover protective structure only protects the operator when the seat belt is fastened, keeping the body inside the protected zone during a rollover.

Hydraulic accumulator precharge

Nitrogen precharge is typically set at one-half to two-thirds of minimum working pressure. Oil at the gas valve means the bladder or piston has failed.

Confined space atmospheric limits

Entry requires oxygen between 19.5 and 23.5 percent, plus testing for hydrogen sulfide, carbon monoxide, and flammable gas before and during entry.

Torque-to-yield fasteners

These fasteners are tightened to a torque plus a specified angle and stretch permanently, so they must be replaced rather than reused.

Cylinder bore taper measurement

Use a telescoping gauge and outside micrometer at top, middle, and bottom in two axes ninety degrees apart to detect taper and out-of-round.

Bearing press fit rule

Press force is applied only to the interference-fit race: the inner race when fitting to a shaft, the outer race when fitting into a housing.

Series versus parallel circuits

In series, current is common and voltages add. In parallel, voltage is common, currents add, and total resistance is below the smallest branch.

CAN bus resistance check

With power off, resistance across CAN high and low should read about 60 ohms from two parallel 120 ohm terminators; 120 ohms means one terminator is open.

Voltage drop testing under load

Measure voltage drop with the circuit energized and loaded; more than about 0.5 volts on a 12 volt path indicates excessive resistance in cable or connection.

Parasitic draw threshold

After modules sleep, a healthy machine draws under roughly 50 milliamps; a higher reading points to a stuck relay, module, or accessory.

Hydraulic horsepower formula

Hydraulic horsepower equals flow in gallons per minute multiplied by pressure in psi, divided by 1714. One gpm at 1000 psi is about 0.58 hp.

Cylinder force calculation

Force equals pressure times piston area. Retraction force uses bore area minus rod area, so retraction is faster and weaker than extension.

Aeration versus cavitation

Aeration produces foamy, spongy oil from air ingress. Cavitation is a knocking noise from vapor pockets caused by a restricted inlet or cold oil.

Load-sensing hydraulic systems

The pump varies displacement to hold a fixed pressure margin above load pressure, reducing energy use and heat at low demand.

Gear ratio torque effect

Ratio equals driven teeth divided by driving teeth. A 3:1 reduction triples output torque while dividing output speed by three.

PTO standard speeds

Standard PTO speeds are 540 rpm at 540 engine rpm and 1000 rpm at 1000 engine rpm on older tractors; economy modes reach rated PTO speed at lower engine rpm.

Driveline universal joint phasing

On a two-joint shaft, yokes must be in phase and joint angles at each end equal, otherwise vibration and rapid joint wear result.

Front axle tire lead

Mechanical front-wheel-drive tractors run front tires about 1 to 5 percent faster than the rear to aid steering; wrong sizes cause driveline windup.

Diesel compression ratio range

Diesel engines typically run 14:1 to 23:1 compression. Low cranking compression from worn rings or valves causes hard starting and poor power.

Valve lash clearance effects

Too little clearance holds valves off their seats and burns them; too much causes noise and reduced lift. Set to specification hot or cold as stated.

DPF regeneration temperature

Diesel particulate filter regeneration needs exhaust temperatures above roughly 550 degrees Celsius; excessive idling and short cycles load the filter and cause derate.

Superheat and subcooling

Superheat is evaporator outlet temperature minus evaporating temperature, typically 5 to 10 degrees Celsius. Subcooling indicates charge and condenser condition.

Refrigerant recovery requirement

Refrigerant must be recovered, never vented. Evacuate below 500 microns and hold vacuum to confirm no leaks before charging.

Seeding rate calibration

Rate equals seed count per hectare times thousand kernel weight, adjusted for germination and purity; verify by catching seed over a measured distance.

Plant population from row counts

Population per hectare equals plants per meter of row divided by row spacing in meters; confirm with a field count after emergence.

Combine total loss target

Acceptable total harvest loss is typically near 1 percent of yield, split between separator loss behind the machine and cleaning shoe loss.

Forage harvester length of cut

Theoretical length of cut depends on feedroll speed relative to cutterhead speed; shorter chop packs better but raises power demand.

Sprayer calibration formula

Gallons per acre equals gallons per minute per nozzle times 5940, divided by speed in mph times nozzle spacing in inches.

Nozzle flow versus pressure

Nozzle flow varies with the square root of pressure, so doubling pressure increases flow only about 41 percent, making pressure poor rate control.

RTK correction loss

RTK accuracy depends on a radio or cellular correction link; losing correction degrades guidance to autonomous accuracy within minutes, so monitor correction age.

ISOBUS plug and play

ISO 11783 lets displays, controllers, and implements interoperate; confirm the task controller and section control functions are enabled for variable rate work.