Definition of Terms
The following is a list of terms and abbreviations with definitions unique to tractors.
3-point Hitch. A popular standardized mechanism for attaching implements, consisting of an adjustable top (pivot) link centered above two lower (lifting) links. Category 0, 1, 2 or 3 refers to both the size of the connecting pins and the strength of the components, with category 0 being the smallest (often seen on garden tractors and implements) and category 3 being the largest (often seen on large agricultural equipment). It is usual for the 3PH to supply lifting force via the hydraulic system, to raise an implement, but rare for it to exert downward force.
Crawler. A vehicle equipped with tracks or treads, like a tank.
Differential Lock. A device for temporarily locking the rear differential to achieve better traction.
Draft Control. A mechanical linkage that automatically adjusts the towing characteristics of an implement like a 3PH plow.
Drawbar. A flat horizontal bar attached to the rear of the tractor, used for dragging or towing. May be attached to the frame at a fixed height, providing the ability to vary the distance between the tractor and implement to be towed. Alternatively, may be attached between the lower links of the 3PH to provide variable height, but at a fixed distance from the tractor.
ROPS. Roll Over Protective Structure. A roll bar or similar device to help protect the driver in case the machine tips over,is a cab or frame that provides a safe environment for the tractor operator in the event of a rollover. The ROPS frame must pass a series of static and dynamic crush tests. These tests examine the ability of the ROPS to withstand various loads to see if the protective zone around the operator station remains intact in an overturn. If you need sunshade (canopy), the ROPS is necessary to support the sunshade. It can be folded, so when you work amoug trees you can put it down to lower the tractor height.
Fast Hitch. AKA Quick Hitch. An alternative, two-point mechanism for attaching implements, in which two bayonet arms on the implement fit into two receivers on the rear of the tractor. Incompatible with three point hitch. Often seen on industrial tractors.
Hydraulics. A system of pressurized oil which provides power for raising and lowering the 3PH and which can be used to operate attached or towed implements having hydraulic pistons and cylinders. "Live" hydraulics maintain oil pressure to the system even when the clutch is disengaged.
Hydrostatic transmission. A hydraulic transmission which varies the tractor's forward or reverse speed within a gear range based on pressure applied to a lever or pedal. Also allows instant transition between forward and reverse direction without the use of a clutch.
Loader. A bucket loader attachment, usually hydraulically operated and front-mounted. Light weight models are used for scooping and moving loose materials, such as manure, gravel, snow, etc. Heavier weight models can be used for digging. Loader is also used to refer to an industrial machine equipped with a front bucket.
PTO. Power Take-Off. An extension of the drive train that allows power to be mechanically transfered to other machinery or implements via a removable driveshaft with splined couplings. PTOs can be located in the rear, middle (belly), front and/or, rarely, side of the tractor. Some standards exist for PTO speeds and driveshaft connections, as described in the table below. Unfortunately, some manufacturers have chosen to create their own "proprietary standards," which can make interoperability of implements difficult. "Live" PTOs continue to rotate independently of the tractor drivetrain. "Semi-live" PTOs can be engaged and disengaged in conjunction with the tractor drivetrain by operation of a two-stage clutch.
Remotes. Hydraulic inlet/outlet pairs at different locations on the tractor for connecting hydraulically operated implements. 2-way valve means a hydraulic valve for hydraulic output, usually we recommend customer choose this option, as this valve will offer more power/oil pressure when you use implements on the tractor.
TLB. Tractor-Loader-Backhoe. A tractor, usually industrial, equipped with a front mounted loader and rear mounted backhoe.
Walking Tractor. A two-wheeled tractor which is operated by someone walking behind it. Also called a walk-behind tractor.
Weights. Ballast added to the tractor or implement to improve balance, traction, stability or digging force. Tractor weights include calcium solution in the tires (usually rear only) to improve traction and/or balance when using a loader, suitcase weights -- slabs of iron held together by a U-shaped bolt and attached to the tractor frame, wheel weights -- circular or semi-circular slabs of iron secured by the wheel lugs, and a weight box -- a rigid box attached to the rear of the tractor, filled with small stones or wet sand, to improve balance when using a loader. Implement weights include sand bags, cement blocks, large rocks, etc.
Single Stage Clutch & Dual Stage Clutch. Simply speaking, dual stage clutch means the clutch can allow seperate disengagement of the PTO. When a live PTO works with the use of a two-stage clutch, pressing the clutch half-way will disengage the transmission while pressing it fully will disengage the transmission and the PTO. This allows the operator to slow down or change gears while the PTO is still operating. The single stage clutch stopped both the pto and tractor when pushed. The dual stage clutch stopped the tractor at about half-way thru the stroke and then you pressed the clutch all the way to the floor to stop the pto.
Fully-closed hood means the engine bonnet which can cover the whole engine in. Some customers do not like this as they hope the engine can be better radiated.
Shuttle shift means you have a F-N-R shifter, usually at the left side of the seat or on the steering column that is separate from the transmission speed and range shifters. If you have to come to a complete stop to shift from forward to reverse, using the clutch, you have "non-synchro" shuttle and a dry clutch. If you can shuttle shift between forward and reverse without grinding the gears while the tractor is moving, but still need to use the clutch, you have "synchro-shuttle".
Shuttle shift transmissions have been used for many years on tractor loaders. These may be mechanical or hydraulic. Mechanical shuttles require using the clutch to change direction, but they are synchronized. Hydraulic shuttles can be shifted with out using the clutch. Either way, these transmissions allow the operator to change directions with out stopping. They allow for similar speeds in forward and reverse and increase productivity with a loader.
A shuttle type transmission has a method of going from forward to reverse quickly for "shuttling" back and forth such as in loader work. There are a two types of shuttle trans. in compact tractors these days:
1. A gear type where a forward gear (usually 1-2) is aligned with reverse in the shift pattern or they may have a seperate lever for this function. To use these one still has to clutch but the time spent shifting is reduced.
2. A hydraulic type that engages the clutch automatically without the driver having to. Again, time spent shifting is reduced.