Thursday, March 09, 2006
By Isaria K.Mwende
Today, the challenge of addressing labour in the farming community in Tanzania is become even more urgent. The drudgery, poor timeliness and low productivity of the hand power and the reduction in labour available in the household to undertake farm work are demanding for a more efficient source of power. Tractor power is among the promising options. The escalating cost of new tractors has forced some farmers into considering the purchase of secondhand makes. The recounting which follows is meant for you who contemplate to buy a used tractor.
A second hand tractor can be a good investment and a good tool at a low cost if you know how to make a good and careful selection. You can buy a second hand tractor from a dealer, from a friend or some other farmer or at an auction.
Buying from a reputable source is the safest route for an inexperienced buyer. If you are buying from a dealer, ask if there is a guarantee or warranty given in writing, even if it is only for three months. Beware of tractors sold in auctions. In this case, have a thorough check of the machine before the day of the auction. If you are buying from a farmer, try to find out why he is selling the tractor. If it is possible to find the tractor operator, ask him if the tractor has given a lot of trouble. It is also important to find out if spare parts for the tractor you intend to buy are available locally.
Below are some things you can do to tell if there is something seriously wrong with the tractor and that it is free from hidden problems. If you have no experience with tractors, take a friend with you who has experience and can do these tests. Otherwise find a mechanic or mechanization technician to assist you.
Start with the tractor’s age, model and hours worked. Ensure that the claimed hours tally with the overall appearance of the tractor and the work that it has been doing. Does the machine look as if it has been cared for? Look beyond a new coat of paint. Try to see what is behind it.
Check the air filter: If it is a disposable paper filter, it will have two rubber seals glued at both ends of the cartridge. Check that these seals will not let air through. If they do, it means that dust may have been leaking past the filter and gone into the engine. If there is dust in the engine it is very serious.
Check carefully for oil and fuel leaks: You might not see any leaks straight away because the tractor may be steam cleaned and degreased before it is sold. In any case, look for oil or fuel spots on the ground under the machine. Streaks of oil across tires and hubs may mean a defective shaft seal.
Turn on the ignition: On most tractors there are lights, one for oil pressure and the other to show that the alternator is charging. They should both go on when the key is turned.
When you start the engine: Both lights should go out. If they do not go out, then there is trouble.
First thing before you start the tractor remove the radiator cap (on a cold engine). A creamy white deposit on the underside of the cap indicates that exhaust gases may be leaking into the coolant system. Then start the tractor and look for bubbles at idle. Be careful not to confuse foam caused by the coolant circulation. Presence of bubbles confirms the earlier observation. A damaged cylinder head gasket or cracked engine block is the cause.
Look inside the radiator for signs of corrosion. Also examine the outside of the radiator for damaged fins. Stains along the fins usually indicate a leak.
Warm up the engine: Check that the temperature gauge works.
Listen to the engine as it warms and watch the exhaust: If the engine does not run completely smoothly and there is blue-white smoke coming out of the exhaust, it probably means that something is wrong with the fuel-injection system. This can be very expensive to repair. If the tractor blows a lot of dark smoke the piston rings could be worn. In an extreme case, the breather tube outlet gives out caked oil or an obvious flow of exhaust gases. This usually means the tractor needs a complete engine overhaul.
Press the clutch and see how far you have to push it down before you can change gear. If it is difficult to get into gear, check to see if you can take up any slack through the clutch adjustment mechanism. If you cannot, it probably means that the clutch plates will have to be renewed soon.
Release the handbrake, let out the clutch and see how smoothly the tractor starts to move. Use all the gears in both ranges. Check that the gear lever is not too loose in any gear and check that it does not jump out of gear.
In low range put the tractor in first gear and open the throttle to 2200 rpm. Stand on the brakes. This will be the same for the engine as pulling a plough. Listen for any squeal or whine from the gearbox or differential, or any tapping noises. These noises mean that there is bad wear, such as broken gear teeth or damaged selectors. Gearbox and differential repairs are very expensive.
Check the hydraulic filter: There are two types, one is disposable like an air filter, the other is a magnetic rod, which picks up any metallic dirt in the system. Check if the filter is dirty. If it is dirty, test the hydraulic lift system very care fully.
Check the hydraulic lift system: You will need a plough to check that it works properly. It must lift smoothly and not jerk. When the plough is lifted it must stay at the same height even with the engine at idle. It is even better if you can check the lift in a field. The plough must not dig itself under the ground or drag on the top of the ground.
Check to see if any hoses are becoming rotten.
Check the grease nipples: If they are clean it probably means that the tractor has not been maintained regularly. Remove the grease fitting and examine the interior. If a component is loose and can be wiggled, excessive wear has taken place.
Check the power take-off (PTO) if it is working. Engage and disengage the PTO several times and watch the output shaft. See if it runs smoothly or it wiggles. Listen for any strange noises when it is running.
When you have run the tractor for a while and the engine is hot, check again for oil and diesel leaks.
Check the steering system, tyres and wheels: Rough movement of the wheels may indicate bent hydraulic cylinder rods, worn steering gears (backlash), worn or seized knuckle joints. Tractor wheels will rust with age and weaken. Look for wheels that have been bent or cracked and welded. Check for an uneven wear of tyres. Replacing tractor tyres and wheels can be expensive.
Once you are through with this exercise, make a list of all the things that are wrong and which need fixing. Work out the cost of repairs. Then decide if you still want to buy the tractor. Show the list to the seller to see if you can get a better price for it.
Whether you buy a second-hand or new tractor be sure you get an operator’s manual. Read it carefully. It will tell you how to get the best use from the tractor. If you want to do a lot of repairs yourself, buy a workshop manual. It will tell you how to do almost all repairs. The workshop manual is expensive. It must be ordered from the manufacturer.
In case you did not get the operator’s manual, consult a mechanization technician to assist you to make a service chart on a piece of paper to cover the next 1000 hours that the tractor works. Greater care and preventive maintenance is needed to prolong the life of the tractor.