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Sikubaliani na hayo maelezo SABABU mfumo wa suspension unaanzia kwenye tyreWhy does a tractor not have a suspension system?
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Vigneshwarraj, ✻Craze for Car and Know few aspects about them✻
Updated Dec 26, 2015
Tractors , earth mover and other heavy commercial vehicles do not have suspension for the following reasons
First its required to get know what are things affected by a suspension system.
If a suspension is installed in a vehicle , then the vehicle will not have constant motion body. The body tend to oscillate in the direction of axis of the spring.
This oscillation can change ride height while operating . The condition may be while working or moving.
The body will start to roll , take this example

Consider the above system. Assume as if the brown mark is the support attached to a vehicle.
Ideally we say that the spring oscilates up and down. Practically a spring can also bend causing irregular motions.
Under varied driving the spring will oscillate in multiple axis . The mass will start to bounce in all possible directions . Also the distance between the mass and the support will be changing constantly.
If the car accelerates faster the mass will fall back . If it brake faster then the mass will take a nose dive (or moves forward).
Now the answer
In a tractor mostly used to pull loads or equipped in farming conditions , if there is a suspension installed , then the ride height will be changing. So it may affect the mass being pulled.Consider the tractor is ploughing , there will be load trying to make the tractor stop as its inserted in the ground. This may cause the body of the tractor to tilt backwards

(assumed the plough is attched to rear axle).
This reaction may cause the spring to bend .
Also the steering heavily will affect the steering characteristics.
This also the same reason why earth movers ( build dozers )

If the back bucket or hoe pitches(yaws) at vertical axis the body will roll to the direction faced by the hoe.
Also the depth of excavation will change under these circumstances.
These equpments ( tractors and back hoes) will work in slopy hills. Under these position the body will roll along the slope

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Rohit Kohli, works at AGCO
Written Jan 10, 2016
"Suspension" system's main function is to stabilize the vehicle and isolate the vehicle occupants from shocks/undulation from road/field surface.
Do tractors have a suspension system to meet the above objective - YES !!!Is it as complex, or well laid out as other vehicles - NODo tractors have any shock absorption mechanism for drivers - YES
Please read below to understand a Tractor's suspension/shock absorption system:
Tractor's front axle (on-chassis) suspension system
Almost all farm tractors have a pivoted front axle. Shown below is a front axle assembly of a 4WD tractor (image source - SAE Link)

The center pivot helps the front left and right tire to move up and down to follow the field contour. In a 4wd tractor, it helps steer-ability and tractors formward/backward motion. Pretty much what a truck/bus/car suspension does, but with a altogether different technology.
Haven't been able to find a better picture, but the below pic tries to capture the movement of front axle on an undulating surface.

Tractor's seat suspension (or rather shock absorption) system
Tractor operators do need isolation from very severe undulations, vibrations arising out of machine operation. All tractors (even the primitive ones) have some sort of seat suspension to isolate the operator from shocks/ vibrations. Here are few examples:
A vintage/ scrapped tractor.. notice the cantilever hanging seat supported by a coil spring (image source - Link)

A schematic diagram of a seat with air suspension (image source - Sears corporation Link)

Tractor's cabin suspension (or rather shock absorption) system
Cabin tractors use suspension system to mount the cabin. Apart from adding additional level of comfort, the cab suspension also protects the cabin frame/glass, panels in the cab, electronic displays, and various other gadgets from breaking away under shock load. Here is an explanatory pic (image source - Case website (Link):

Summary - Tractors do have suspension/ shock absorption system. However, because of different speed and field requirements, the on-chassis suspension components are limited. The manufacturers compensate that by providing state-of-the art seat and cab suspension systems.
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Abhishek Jaiswal, works at Century cement,Baikunth.
Written Apr 17, 2016
Well tractors are supposed to maintain a constant depth in ploughing/digging. For this it requires the movement of the body to be restricted so that we do not disturb the main tractor functions.
If we have a suspended tractors which bounces too much over undulations in a field then we can't expect to have a constant ploughing depth which is a requirement in agriculture.
Suspensions also affects the off road stability.
As the speed of the tractor is less and the tyres big(which absorbs more shocks),the need of suspension is felt less.
Thank you.
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Jaspal Singh, Doing nothing in Farm Equipment sector...
Written Dec 29
Tractors have hydraulic system to use attached implements to prepare the field for next sowing.
There is a term called "Draft Sensing". Draft means the resistance of soil to the attached implement and the sensing means the ability of tractor to sense the resistance of soil.
Now when tractor runs in field, the draft is offered by soil and sensing is done by tractor hydraulic feedback mechanism. This help to achieve uniform depth of cut.
See below image:-
http://manuals.deere.com/omview/...
If you use suspension system on tractors, then the draft sensing will not work uniform depth of cut may not be achieved.
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Devang Darode, member of BAJA team, studied vehicle dynamics extensively in & outside classroom
Written Dec 19, 2015
The reason. Is pretty simple actually. But before moving to the answer you need to understand the fact that the purpose of suspension system is not only to absorb shocks. It serves many other extremely crucial functions.
Some of these functions are preventing vehicle from rolling and pitching, maintain continuous contact between wheels and ground on uneven and bumpy roads and of course to reduce the impact of force transmitting to the vehicle frame.
Now if you'd observe closly you'll realize that all these phenomena are dominant st very higher speeds. And as Tractors and Excavators are very low speed vehicles, the don't face any of these problems. And hence they do not need an excessively well built suspension system.
I hope this helps. This being my first Quora answer, I'd appreciate constrictive suggestions.
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Harsh Patel
Written Dec 30
tractor is not made for comfort you.
it is made for farming. where only weight and torque is matters.
if it has a suspension, the tyres likely to loose friction or due to suspension,
if the suspension given between tyre and diff. the tyre will probably ran over the hard soil and will slip if the attached equipment is stuck with hard soil.
thats why no suspension given in tractors. Only small coil springs fitted beneath the driver seat.
mfno tractor suspension yake inapatkana ktk tyre la Kati je ushawah kujiuliza kwann tairi la Kati la tractor lnajazwa 15psi? na sio 28au30psi kwenye magar ya kawaida?
