A vacuum tanker’s workload will be its busiest in the coming weeks, so now is the time to ensure everything on the spreader is in tip top shape.
Alex Heath speaks to Ollie Eyers, foreman at Chippenham based S.W. Hire, for his advice on what to look out for...
With health and safety both in the farm yard and on the road, as well as nutrients legislation all top priorities, it is vital your slurry tanker is performing at its optimum.
Leaking seals, poor braking and uncovered pto shafts all run the risk of landing farmers in ‘it’ so to speak.
AS with any piece of kit, safety should be a top priority and plenty of attention being paid to the pto shaft driving the pump.
With all but the newest and swankiest tankers requiring the operator to dismount the tractor and go within feet of the pto shaft, the guard should be present and in good condition.
Likewise, the shaft should be free of dents and burrs and well-greased, to allow for a full telescopic motion, vital when going over undulating terrain to reduce stresses put on the tractor and pump housing, says Mr Eyers.
Universal joints should be well greased and checked for excess play and replaced if needed.
To the heart of the machine and its vacuum pump. The most critical point to bear in mind here are the oil levels, including the gearbox and crucially the vacuum pump.
The vacuum reservoir should be checked and topped up daily, as the oil in the vacuum is imperative to its performance while sucking and blowing, as well as vane longevity.
The oil cools and lubricates the pump’s vanes as they slide in and out of the pump’s rotor, while spinning to create pressure. Mr Eyers says it depends on the make of the pump as to the frequency of oil dropping, but a drop should be from every second, to every four seconds, generally speaking.
Reading the manual will state what rate oil should drop at, and it is vital this is adhered to. Over oiling can have an adverse effect, gunging up the slots in the rotors, stopping the vanes from sliding freely under centrifugal force and consequently causing excessive wear.
When running the pump if it takes a long time to build pressure, chances are the vanes are worn or cracked, so need replacing. This is not necessarily a big job and can be done with the pump left in situ on the tanker, says Mr Eyers, costing between £130-£205 depending on the size of the pump.
Kits typically include new vanes, seals and gaskets. Removing the rear of the pump housing will give access to the rotor.
This is easily removed and needs a good clean, ensuring the vane slots are free of debris and burrs, allowing the vanes to move freely. A steam cleaner is the best tool for this. Using a piece of fine sandpaper, remove any surface rust from the inside of the pump housing.
When reassembling with new vanes, coat them in a thin layer of oil. While the pump is apart, the best advice is to check and change any bearings and seals, especially the rear support bearing for the input shaft, which takes the most abuse. When reassembling, new gaskets are needed.
Gearbox oil level is also important and should be regularly checked and topped up. If the oil appears milky, this will be water contamination, so the gearbox should be drained and refilled with SAE 90 oil.
However, this should be done carefully and as per the guidelines on the filler cap, as too much oil can lead to blown seals.
OFTEN, failing to build and maintain pressure is not down to a faulty pump, but rather leaking seals on the filling and spreading points of the tank.
Because of the pressure that gate valves and seals are subjected to, it is not uncommon for the edges of the slide to be worn or chipped from sand and stones that gets blasted past them.
If this is the case, straightening the edge out with an angle grinder can be a quick fix. Inspect the seals around the valve, as any cracks or splits in these can let air ingress while filling, preventing the vacuum, or conversely letting slurry seep through when in transit.
Replacing these seals is a minimal cost of about £14 per seal kit, however, efficiency of the tank will increase dramatically.
While inspecting the gate valves, check to see if the valve stays open on its own, or requires holding or propping open. If it needs assistance, tighten the bolt on the handle at the pivot point so that there is more resistance, thus holding the gate open.
At the rear of the machine, the spreading gate is usually hydraulically controlled, but follows the same principals as the other gate valves.
Check for leaks around the hydraulic ram, and associated pipe work.
IT is critical that the running gear of the tank is well-maintained due to the weight, often on a single axle. Mr Eyers advises jacking each side of the tanker up so the wheel freely rotates.
He says bearings should be checked and adjusted to reduce unwanted movement. Obviously brakes also need adjusting with Mr Eyers a big advocate for easily adjustable commercial axles.
These have slack adjusters that can be adjusted and set correctly with the tank on the floor, by turning the adjuster until it is tight then undoing it a half-turn.
Older style six- or eight-stud axles require a lot more time and effort to get them running properly, and have to be jacked up to do so.
Sight gauges need replacing when they have become cloudy, as when removed for cleaning they will generally shatter. Mr Eyers says he expects to get three years of service from the sight gauges before they are replaced.
Other things to consider are making sure all tyres, hydraulic pipes, suction pipes and the body of the tank are free of defects, to ensure hassle-free slurry spreading.