Farm Ireland

Tuesday 25 October 2016

Machinery: Lighten the load

Derek Casey

Published 13/01/2016 | 02:30

A properly maintained tanker is essential for getting the optimum value from slurry.
A properly maintained tanker is essential for getting the optimum value from slurry.
The exit valve is normally held closed by a spring or gas cylinder and opened hydraulically. Oil leaks point to a loose union or dodgy seals.
Wheel nuts and bearings should be checked daily during spreading.
Make it your New Year's Resolution to replace any damaged PTO guards on the farm.

The slurry spreading dates re-open this week in most counties. Zone C counties must wait until the end of January before they are allowed to get slurry out, but in the meantime and until the weather improves there is now an opportunity to get your tanker ready for the big workload ahead.

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The pressure is now on to get some slurry out, and many farmers are at their wits' end with slatted tanks full to capacity. Ground conditions will need to be weighed up on an individual basis because heavy tankers will do more harm than good in soft conditions.

If you have the storage space available, you are better off waiting for things to firm up a bit more.

Contractors are reporting brisk demand and booking in advance, with phone calls from farmers looking to get slurry out once conditions improve.

Regardless of whether you are using your own equipment or hiring someone in to do the job for you, a properly maintained tanker is essential for getting the optimum benefit from your slurry.

It is a hugely valuable and cheap nutrient source on the farm, but really it is only as good as the spreading system that delivers it.

Slurry has to be used wisely to give the best results in terms of early grass growth, and key to this is how well the slurry tanker is spreading.

There are a number of things you can check on your slurry tanker before the season kicks off. The aim is to ensure it is spreading correctly and that your grass is getting the best nutrient boost possible.


It sounds simple, but first remember to wash the tanker. Begin at the drawbar and work back as this will allow you to better see any defects in the body. Wear on the drawbar is inevitable due to heavy loads, so be sure to pay close attention to this area. Wear is also possible at the pivot, particularly if it hasn't been greased in a while.

Check the PTO guard for any wear and tear. Guard safety is hugely important on tankers because on all but the newest models the operator still dismounts the tractor during filling.

End of year statistics from the Health and Safety Authority show that the greatest number of PTO-related accidents happen due to limbs and loose clothes becoming entangled in an uncovered spinning shaft. Why not make it your New Year's resolution to replace any damaged guards on the farm with brand new safer units?

Staying on the PTO, with the tractor turned fully off wriggle the PTO joints and knuckles. If there is any movement change worn items before they self-destruct during the season.

Check that the shaft can slide in and out without sticking; if it binds under power it can't telescope as the tanker crosses bumps and dips, so high forces are fed into the pump gearbox and tractor potentially causing extensive damage. Replace a binding shaft if separation, cleaning and re-greasing doesn't manage to free it up.

Check the pump input shaft as well - in particular, look for oil leaks where it leaves the casing.

Pump gearbox

The main areas are the filler plug, drain plug and level plug. Remove the level plug and some clean oil should be allowed to dribble out. If no oil appears, then top it up with some SAE 90 gear oil. If you notice that the oil is milky, this means it is contaminated with water.

Drain the oil and replace with new oil. Be careful not to overfill the gearbox as the seals may blow.

On some pumps a saddle tank holds lube for the pump's internal rotor vanes. Clean the area around the dipstick before pulling it out to prevent dirt dropping into the reservoir. Top up to the dipstick mark with fresh vacuum pump oil (not gear oil).

Keep the tank as full as possible as this helps to cool the pump. The oil dropper should drop oil at a rate of about one drop every two seconds - anything less and you risk the pump vanes seizing up. Oil lubricates the vacuum pump vanes and diverter and then leaves through the exhaust.

Have a look and clean off the clock pressure gauge. The clock usually shows tank pressure on one side and the tank vacuum on the other. If the hand doesn't return to zero, then replace it with a new one.

Also check the sight glasses; if they have turned cloudy, brittle or are hard to remove they might need replacing as well. These gauges are important to let you know if the tanker is performing properly so they should be kept clean at all times.

Gate valves

Gate valves on the slurry tanker control the flow of slurry into and out of the tank. Common problems are leakages or worn edges.

Check the slide's leading edge as it can be chipped or worn by stones, preventing an effective seal. Undo the operating rod's gland nut and take out the O-ring seal - if this is broken then air or slurry will leak past it and performance suffers.

These parts can be replaced easily, aren't expensive but make a big difference to performance.

The exit valve is normally held closed by a spring return ram or gas cylinder and opened hydraulically.

A worn or damaged slide, a broken spring or a failing return cylinder could mean a big mess on the road, so these parts need regular inspection.

Oil leaks at this point typically point to dodgy ram seals.

Brakes and tyres

Tyres need to be in good condition especially if you are doing a lot of road work. Inflate the tyres to the tanker manufacturer's recommended figure and remember to check and clean the lights on the tanker regularly.

Commercial axle brakes found on a lot of slurry tankers are easy enough to adjust. Jack the wheel so it's just clear of the ground, supporting the axle on stands if necessary. Then move the adjuster until the brake locks the wheel. Back off the adjustment until the wheel just turns freely; repeat for the remaining wheels.

For the handbrake, check that it moves easily and that its ratchet works. Check that the handbrake is fully applied well before the lever reaches the end of its travel. If that is not the case, shorten the cable until it is - then see that the wheels still turn freely with the handbrake off.

Finally, when the wheel is jacked it's a good opportunity to check wheel bearings as well. When the weight is off the wheel move it back and forth. A little movement is ok but if there is a lot of movement the bearings need to be adjusted.

Calibrating your tanker

While some farmers and contractors have made the switch to more sophisticated application methods like shoe and band spreaders, the vast majority still use splash plate tankers.

To make the best use of the nutrients in slurry it is important to apply it evenly, at the right rate and at the right time. Farmers talk about application rates all the time, but in practice it can be hard to be sure of your rate when using an older tanker.

One method of determining the right rate is to measure the area covered with one load and relate this back to the size of the vacuum tanker.

The width of spread (in metres) multiplied by the length of the run (in metres) for one load, divided by 10,000, will give you the area covered in hectares. If you prefer old money, the width of spread (in yards) multiplied by the length of the run (in yards) for one load, divided by 4,840 will give you the area covered in acres.

Discharge rate

The discharge rate can be measured by timing how long it takes to empty one load. Divide the capacity of the tanker by the time in minutes taken to empty it. For example, a 1600-gallon tanker emptying in 3 minutes and 40 seconds gives a discharge rate of almost 440 gallons per minute (2m3 per minute). The discharge rate from most tankers is usually about 2m3 per minute, but to be sure measure it and adjust your rate accordingly if you are too high or low.

Indo Farming


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