Chapter 12: Engine application and selection

spark arrester

A component in the exhaust system that redirects the flow of exhaust gases through a screen to trap sparks discharged from the engine

Belt guide

A component that helps to retain a belt within the confines of the pulley groove

Differential gear box

A component that provides drive wheel traction with independent drive wheel rotation rates, allowing OPE with wheels to easily turn corners

Belt guard

A component that provides protection for a pulley/belt combination to prevent accumulation of debris near a rotating members from outside objects

Creep

A condition of a slow longitudinal movement caused by external forces

Belt tension

A condition that occurs from a belt being pulled or stretched

Wedge effect

A condition that occurs in a belt drive system when a V-belt wraps around the diameter of a V-shaped pulley, causing the normally flat sides of the belt that contact the groove in the pulley to bulge outward causing the belt to form a wedge

Power curve

A graphic representation of horsepower and torque output of a specific engine in a test laboratory

recommended maximum operating BHP curve

A graphic representation that indicates engine power at 85% of maximum BHP

Pulley

A grooves rotating wheel with a belt around a portion of the circumference and is used for moving loads

Axial load

A load applied parallel to the shaft

Synchronous drive system

A mechanical drive system that is designed to provide constant, positive engagement between the drive and driven member of the system

Flexible belt drive

A mechanical drive system that uses a resilient flexible belt to transfer power between a drive and a driven shaft

Asynchronous drive system

A power transport drive system used on outdoor power equipment to transfer power from one piece of equipment to another

Friction disc variable speed drive system

A system that has a friction driven disc in perpendicular contact with a smooth drive disc in perpendicular contact with a smooth drive disc attached to a power source

Decibal

A unit of expressing relative intensity of sound on a scale from 0-140.

Muffler

An engine component fitted with baffles and plates that subdues noise produced from exhaust gases exiting the combustion chamber

Booster fan

An engine component mounted on the flywheel side of the engine that consists of a hub with bosses and tapped holes for connecting driven equipment components

Total enclosure installation

An engine installation that does not allow a person to touch the engine by hand nor see the engine by normal line of sight vision

Oversized engine

An engine that is typically capable of producing 20-30% more power than required by the application at full load

Undersized engine

An engine which consistently works close to maximum capacity with little or no reserve power

Belt wrap

The percentage of the belt surface in contact with the pulley circumference in a belt drive system

Maximum BHP curve

a graphic representation that indicates engine power developed with the throttle in WOT position across the usable engine rpm range in a test laboratory

Variable - speed drive

a mechanical drive system component that provides variable output belt drive speeds without changing the speed of the drive member or engine

Notched V-belt

A V-belt that has a curvilinear tooth pattern on its drive surface

Fully enclosed belt guide

A belt guide installed on outdoor equipment to help retain drive belts in position when disengaged

Semi enclosed belt guide

A belt guide that provides partial pulley coverage based on the specific system belt wrap a and angle of belt entry and discharge

L bracket belt guide

A belt guide that retains a v-belt for the engagement and disengagement process as well as provides a positive release of the belt form the pulley when the system is placed in the disengaged position

Stationary pin belt guide

A belt guide that uses pins to retain a belt within the grooves of a pulley

Rigid PTO coupling

A PTO coupling designed to transmit rotary motion where connected shafts are positioned in precise lateral and angular alignment

Flexible PTO coupling

A PTO coupling with a resilient center, such as rubber, that flexes under temporary torque or misalignment

V-belt

A continuous reinforced rubber belt used to connect pulleys and motors and transfer rotation

Manual friction speed control

A control mounted on the engine that uses a friction lever to maintain an engine at a specific top no-load speed

Adjustable fixed speed control

A control mounted on the engine that uses a speed adjustment nut to maintain an engine at a specific top no-load speed

Remote speed control

A control that allows rather operator to vary engine speed from a remote location

Shear pin

A cylindrical piece of meta, alloy that will tear or shear at a predetermined location and applied torque value

Power take off coupling

A device used to connect mechanical drives such as an engine or electric motor to a driven member

Double V-belt

A drive belt that has two v-shaped drive surfaces

Centrifugal clutch

A drive system component that provides a smooth engagement of a mechanical drive at a specified RPM

Classical V- belt

A flexible drive belt with a single V-shaped drive surface.

Electromagnetic clutch

A flexible drive system component that uses electrical energy to create a positive belt drive engagement for an implement of attachment

High-inertia flywheel

A flywheel that exhibits greater mass than a low-inertia flywheel and is designed to provide the minimum engine inertia required independent of the external parasitic load

Low- inertia flywheel

A flywheel that uses an external load connected to the engine to provide the minimum engine inertia required

Shock load

A force applied to a drive system that causes a sudden, high load to be placed on all drive system components at the same time

Dual groove variable speed pulley

A pulley that has two v-shaped grooves that respond in opposite directions

Idler pulley

A pulley that rotates in the direction opposite a drive pulley

V-shaped pulley

A pulley with a V-shaped groove on its circumference

Service replacement engine

A replacement engine that has the operating characteristics and required features of the original engine but is not supplied by the OEM

Flange coupling

A rigid PTO coupling that consists of two separate flanges fastened together with bolts and locknuts

Spark ignition engine test code

ANSI/SAE J1349-MAR08

Environmental operating conditions

Conditions present which affect engine performance

Fretting

Damage that occurs to machine parts where two contacting surfaces are subject to slippage

Partial enclosure installation

Engine installation that allows partial access to engine components

Open installation

Engine installation that does not have any barriers which impede access of air to and away from the engine

Centripetal force

Force that is required to keep an object rotating in a circular path and is directed inward towards the center of rotation

Torque curve

Graphic representation that indicates maximum engine torque produced at a specific rpm

Slack side tension

Measurable tension on the belt as it approaches the driven pulley

Frequency

Number of vibrations per second a noise contains measured in hertz

Engine power test code - spark ignition and compression ignition - net power rating

Permits both gross and net power ratings

Engine footprint

The area covered by the mounting base of an engine

Tight-side tension

The measurable tension on the belt as it approaches a drive pulley

Slip

The movement of a belt on the face of the pulley when belt tension is too loose

Repowering

The process of replacing the original engine on a peice of equipment with another engine

Engine envelope

The vertical, horizontal, and peripheral clearance space required for an engine installation