Modern agriculture depends on millions of ball and roller bearings and the grease that helps them all roll.
So it’s no surprise that proper greasing goes a long way to ensuring implement wheels keep turning during peak periods and also keeps a lid on maintenance costs.
The job of greasing the bearings typically falls to the operator of the day for that implement.
Decisions on when to grease and how much to pump into each zerk often depend on weather, seasonal rush, time of day and the mood of the operator.
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How much grease is too much? How little is too little? How much grease is already in the bearing? Has the grease lost its oil and turned into a crusty non-lubricating chunk of hard petroleum?
Because we can’t see inside the bearing housing, we don’t know.
To get a firm grasp on the slippery issue, three engineers who work exclusively with bearings and grease offer their advice. Marcus Wickert is manager of technical resources at NTN Canada, John Melanson is engineering manager at SKF Canada and John Munson is with Standard Bearing in Des Moines, Iowa.
The three agreed that the question of too much grease versus too little grease depends on operating speed and application of the bearing more than on the part number stamped on the housing.
“Bearings today are really well built,” said Munson. “Some of the bearings coming out of China lately have a higher degree of precision than the finest Swiss watch. But they all need proper greasing. If you have too much or too little grease, you can still destroy the best bearing ever built.”
“Just keep pumping grease until the seals blow.”
Wickert said the first time he heard someone say that, he thought the guy was joking. But then he realized it wasn’t a joke.
Seals perform two vital functions in agricultural equipment. They keep the grease in the bearing and they keep contaminants out of the bearing.
Bearings running in dirty conditions require a lot of grease, but they also require functional seals. Once the seal is ruptured, it’s only a matter of time before dirt, sand, dust and water get inside to destroy the bearing.
Those factors don’t rear their ugly heads until the machine is working in the field.
The other scenario in which too much grease can cause bearing failure is with high-speed bearings.
“To picture a high speed bearing running in too much grease, just picture yourself trying to run in a swimming pool with water up to your neck,” Wickert said.
“The water creates so much resistance, it takes all your energy just to move, never mind run. If you’re a high speed bearing, that’s what it’s like when there’s too much grease in the housing.
“Now, try running in a wading pool with the water level down around your ankles. That’s doable because there’s less resistance. You don’t waste as much energy or wear yourself out.”
He said high-speed bearings need only the liquid oil they get when the grease warms up.
“If the bearing cavity is full of grease, it creates fluid friction. The excess grease creates heat. The assembly overheats and blows the seals.”
The result will be the same as if the housing is overfilled with a grease gun: a failed bearing.
Melanson said there’s a tightrope to walk when pumping grease. You want enough to push contaminants from the bearing housing, but not so much pressure that the seals blow.
“There’s a fine line between prudent pressure to purge the contaminants and blowing the seals with too much pressure,” said Melanson.
“We all know how much damage contaminants can cause. Try to think of grease as a means of cleaning the bearings and sealing the cavity so no more particles get in there.”
Munson said researchers at Standard have confirmed that the rolling elements only need a thin film of oil, but it must be a constant film.
They have also shown that too much grease prevents the balls and rollers from dissipating heat.
“When a farm implement is working in the busy season, we recommend only one or two pumps per day at each fitting. That’s all you really need,” says Munson.
“A lever action grease gun can generate 2,500 to 3,000 psi of pressure, more than enough to blow the seals. Once you’ve breached the integrity of the seal, it’s open to all kinds of contamination. That’s the point at which your bearing begins to deteriorate.
“Grease guns have so much potential pressure so you can blow out grease plugs when they occur. But don’t use that pressure unless you need it.”
He describes a grease plug as old lubricant that has solidified and is blocking fresh grease from entering the housing. The plug develops when the fitting isn’t greased regularly.
Wickert said grease products used in equipment bearings, wheel bearings, constant velocity joints and other metal-to-metal applications are made up of oil and different thickening agents and additives for each specific application.
“That oil will oxidize,” he said.
“It dries up and disappears into the atmosphere. The oil that was supposed to provide lubrication is now gone. You can’t just replace the oil only. You need to replace the grease.
“The problem with grease is you never know whether or not it’s gone bad and dried out. With liquid lubricants like motor oil and hypoid gear oil, you know.”
This is why implement manufacturers recommend frequent greasing intervals. Even high tech grease products lose their oils.
Once that happens and the old grease becomes solidified, it’s difficult for the grease gun to purge it from the bearing surface. The new grease is more pliable so it takes the course of least resistance, which is to go around the solidified grease plug. Given time, the grease plug basically becomes part of the bearing housing.
Low speed agricultural bearings require large quantities of fresh grease on a regular basis during the working season.
Wickert said contamination from moisture and hard particulate matter is the biggest factor in destroying these bearings. They often fail from too little grease.
“Most bearings in farm equipment don’t run fast enough to pump the lubricant and distribute it around in the housing the way a high speed bearing does,” Wickert said.
In agriculture equipment, most bearing speeds are low but they run with high contamination. Lots of grease is required in these bearings because the grease does three jobs.
Obviously it lubricates the friction surfaces, but it also lubricates the seals so they stay pliable and flexible.
“Fresh grease serves to purge contaminants from the bearings. Incoming grease fills the voids in the housing and forces the grime and grit away from the friction areas. And it repels moisture.
“The bearing units have a metal plate over the seal as a trash guard. There’s a rubber seal inside and a cavity between them. By forcing fresh grease into the housing, past the bearing, you’re giving the bearing fresh lubricant and forcing out the moisture and particles.
“If the bearing is running 10 or 20 rpm in dirty conditions, then fill it with grease. Just be careful not to blow the seals.”
Munson said the biggest problem is that most farm implements are seasonal. The machine works and gets hot for the season, then sits dormant for most of the year.
“While the machine sits, gravity pulls the lubricant down to the bottom of the bearing housing so the top of the bearing is exposed,” said Munson. Grease settles to the bottom faster when it’s warm.
“Over half the balls or rollers don’t have adequate lubricant to protect them from corrosion. This is especially true in combines, but it also applies to air seeders, sprayers, balers, wagons and tractors.”
He said greasing the machine at the end of the workday is probably the best idea, because the old grease is warm and mixes easily with fresh grease. Waiting until morning lets the old grease stiffen and the grease can do a better job of pushing out contaminants when it’s still at operating temperature.
“The problem is that at the end of a long day in the field, an operator just wants to get in the house for a shower and a cold beer. He doesn’t want to waste time greasing machinery.”
Wickert said grease seldom goes bad while the machine is in operation. It typically dries out and loses its oil when the machine is parked for the year, which is why greasing before storage is critical.
The grease is warm and pliable when the implement comes in from the field on the last day of the season, allowing air pockets to form in the bearing housing. They usually form at the top of the housing as the grease runs down to the bottom.
The longer the implement sits, the more the oil tends to oxidize and the more moisture creeps in.
“You get voids and gaps in the grease. It turns dry and hard. Moisture starts corroding bare metal surfaces on the bearings and shafts. You do not want to put the machine into storage in this condition,” he said.
“We’ve done a lot of research to establish the best time to grease ag equipment for storage. For one thing, if you pressure wash your machinery before putting it away, do the greasing after to make sure you purge all the water from the bearings.”
Melanson agreed, “We see a lot of bearing failures in situations where pressure washers are used. The pressure washer forces water past the seal.
“It’s just human nature to want to clean things up good around the seals. People can’t help it. But every time you get the spray close to a bearing housing, you risk putting water inside.”
Wickert said: “If you just blow the implement off with air, make sure you grease it while the weather and the machinery is still warm. Grease doesn’t flow in cold weather, so don’t wait.”
The worst-case scenario involves combines, grain carts and trucks that don’t come off the field until November or December with no heated shop.
Wickert said putting these machines into cold storage without a complete grease job is asking for trouble next year.
“If it’s – 20 C, that grease won’t flow. You’ve got to do it when all the shafts and bearings are warm from running.”
“High summer temperatures aren’t necessary, but if you’ve picked up a lot of contaminants, you’ll do a better job of pushing them out of the bearings with your new grease if the old grease is still warm.”
That might mean a trip to a dealer’s warm shop, which in the long run may be less expensive than putting the machinery away without adequate bearing protection.
Wickert said it’s essential to distribute the grease over the metal surfaces before storage. There will still be bare surfaces that are subject to corrosion, even if producers have pumped in the right amount of grease.
“You should run the machine for a few seconds to make sure every shaft turns. Rotating the shafts will channel new grease to the bearings and the rubber seals. Even if you just turn the shafts by hand for a few rotations, that will help push the grease.”
Munson said that Standard takes the NTN recommendation one step further by suggesting that, if at all possible, farmers should run every piece of equipment at least once during the storage period to circulate grease in the bearings.
“I’d make sure every bearing gets circulated at least once, even the hay wagons and grain carts,” he said.
While some big farms now have the gun-on-a-hose system found in dealerships, those not so lucky still use a hand-held lever-action grease gun.
The cordless electric grease gun is one option. It uses conventional grease tubes but is powered by a rechargeable battery instead of your hand, making it portable and independent of an air line or electrical outlet.
“For an implement like a disc type air drill or a cultivator with coulters, you really want the cavity between the rubber seal and the metal trash guard to be full of grease,” Wickert said.
“I think a battery powered grease gun is ideal for that kind of situation.”
He said the autolube system is another labour saving device that can do a better job of metering out the right amount of grease at the right time.
The grease zerk is removed and a new fitting connected to the autolube system is screwed into the hole. A battery powered pump or a charged gas cylinder dispenses a pre-measured amount of grease on regular intervals when the machine is running.
The timing and volume of grease can be engineered to suit the requirements of the bearing.
“It adds just a little dab to replenish the grease in there and purge the contaminants. So far, it’s mainly used in industry and stationary equipment.”
He isn’t sure if the current state of autolube development would stand up to the abuse of farm implements. Melanson agreed that an automated lubrication system would be the ultimate for farm implements. He thinks it is possible.
“An occasional little bit of grease while the machine is running would be far better for the bearings than a big surge once a day.
“An automated system can probably be installed on just about any type of machine. It’s a question of whether or not it’s financially viable.”
Melanson said SKF has a hub, called the Agri Hub, with seals specially engineered for farm implements.
Wickert warned that some synthetic lubricants are hard on seals because they dry the rubber to the point that it cracks.
“You have to be careful if you’re mixing greases. There are a few greases out there which are not compatible with others. There are different thickening agents that aren’t compatible.
“If you start mixing grease formulas, it can have an adverse effect. You might think you’re doing your bearings a favour with the latest high tech grease, but it could turn out to be just the opposite.”
He said producers should always read the label on the container of a new lubricant and compare it to the label on the previously purchased lubricant.
For more information, visit www.ntnbearings.net or www.skf.com or www.standardbearings.com.
White cockle is a growing problem in prairie fields.
It is tough to control once it reaches its short-lived perennial stage, and its seeds are practically impossible to clean from commercial timothy, alfalfa and clover seed production.
The weed produces large numbers of seeds, has a tough, deep taproot and is difficult to remove from the field once established.
Mature plants are 10 to 30 inches high and have oblong, hairy leaves with smooth edges. Flowers are fragrant, white, about an inch across and open at night.
Research at the University of Saskatchewan has shown that a two stage approach to weed control obtains the best results on white cockle.
Dicamba, Banvel mixed with 2,4-D or MCPA is used in cereal crops when the weed is in the two to four leaf stage. Dicamba is applied at a rate of .12 litres per acre, while 2,4-D or MCPA, in a 500 gram formulation, is applied at .35 litres.
The U of S research has shown that a pre-seed burn off will control seedlings but not perennials. However, work by Ken Sapsford, research associate with the Weed Control Unit at the Crop Development Centre in Saskatoon, indicates that a second application of herbicide can be effective in a cereal crop after glyphosate or a mix of glyphosate and florasulam, Prepass or tribenuron and metsulfuron, Express Pro or 2,4-D.
Group 2 combination products were effective in controlling white cockle in spring wheat. Combinations included thifensulfuron, tribenuron and metsulfuron, known as Precision Pac 23235, tribenuron with 2,4-D and dicamba and Precision Pac 2525, as well as thifensulfuron and tribenuron, but with the addition of MCPA.
Care has to be taken that tribenuron and metsulfuron don’t exceed the recommended rate. As a result, they should not be applied in sequence if they are contained in the burn down application.
Research showed that Prepass may have had such good early control that the weeds weren’t ready for further restriction when given a second shot in the crop.
For legume crops such as alfalfa and clover, white cockle is treated traditionally with 2,4-DB such as Cobutox, Embutox or Caliber, using the 625 grams per litre formulation, at about 1.7 litres per acre.
In established pasture, a mix of dicamba, 2,4-D and mecoprop-p, DyVel DSp, can be applied at a rate of 1.3 litres per acre.
A 30 day grazing restriction exists in any pasture application.
Tillage is also a control option for this weed.
White cockle’s proper name is Lychnis alba and is also known as evening lychnis and white campion.
