Drive Systems

There are a variety of axle and wheel combinations in common use on fire apparatus. Below is a quick look at, and description of each system.
===2WD===
*1 differential
*1 motive axle
**FWD - front-wheel drive
**RWD - rear-wheel drive
===AWD===
*2 motive axles; the latest technology includes slip detection, and variable power transfer at each wheel
*no motive axles; electric motors at each wheel
===4WD===
*2 motive axles
*full time or selectable 4x2
*uses a transfer case, 2 differentials and high/low ranges.
===4x2===
*another name for RWD
*sometimes used to describe a vehicle that can select 2WD or 4WD
===4x4===
*another name for 4WD
*often used to describe a vehicle that can select 2WD or 4WD
===6x2===
*1 motive rear axle
*1 non-motive rear axle (add on non-motive axles are for weight distribution; they most often operate on a lift or retractable axle system.)
*1 non-motive front axle
===6x4===
*2 motive rear axles
*1 non-motive front axle
===6x6===
*2 motive rear axles
*1 motive front axle
===8x4===
*2 motive rear axles
*1 non-motive rear axle
*1 non-motive front axle
or
*2 motive rear axles
*2 non-motive front axles
===8x6===
*3 motive rear axles
*1 non-motive front axle
===8x8===
*4 motive axles
===Tandem===
A generic name for 2 rear axles. May be both motive or 1 motive , 1 non-motive. May also include the single-double wheel configuration, and lift system for 1 axle.
===Single-Double===
This configuration consists of 2 rear axles, 1 motive 1 non-motive. The motive axle has dual wheels and the non-motive axle has single wheels. Very common configuration on coach type buses.
===Dual Wheels===
*the addition of dual wheels to an axle increases weight carrying ability, can increase traction and decrease stopping distance.
**also known as duallies, dually's or DRW.
===Steering===
*steering axles are most often singular, but may be 2, 3 or 4 axles with angular software control or operator controlled "tiller" systems.
===Other===
Terra-Drive Systems offers EZ-Trac AWD, an after-market, hydraulic front-wheel-drive assist system for medium to heavy-duty trucks.
Category:Fire Apparatus