There are two possible causes for when a washing machine jumps and bangs on spin. Either the load is a bad one and unable to be balanced, or a fault is preventing the machine from balancing the load (or causing the motor to surge into spin when it shouldn't). This causes the laundry to be flung around inside. The occasional jumping around may not be anything to worry about, but regular or severe occurrences should be a cause for concern and can cause expensive damage to your washing machine if ignored.
Both these faults are less common these days because manufacturers have built in certain protections, but it's still something that can happen. To differentiate between the two, observe when the problem occurs, if it's during a wash cycle, maybe at random parts of the programme, it may have a fault which really needs an engineer to diagnose as these faults can be intermittent and tricky to diagnose. If it happens when it kicks into the fast spin the chances are it's related to the load inside.
Am I overloading my washing machine?
By out of balance I mean when the washer jumps or bangs quite violently. If the washer is just rocking about on most spins make sure it's on a level floor and that it is properly level.
If a load is out of balance you can often observe the inner drum swaying about or even thumping the sides of the casing a few times whilst it's trying to distribute the load prior to fast spin. Before a proper spin the drum should revolve slowly for a couple of minutes. This is called "distribute" and at this stage you may see large flashes of metal drum on each revolution where all the laundry has settled around the drum but there wasn't enough to cover all of it. If this happens the drum will be out of balance and either refuse to spin, or if allowed to spin may cause the drum to thump around and hit the sides of the casing.
The best way to avoid unbalanced loads in a washing machine
If you try to wash a bulky, heavy and absorbent item, the washing machine is unlikely to be able to get it to balance inside the drum. Or if you put just a few large towels or a heavy item in amongst some very light fabrics the heavy items could bunch to one side of the drum and the lighter ones won't be able to counter-balance their weight effectively. There should be enough items to fit all around the drum. If there's only enough to fill most of the drum, but a section is empty, then it can get out of balance on spin. If the items are all light, then this may not cause a problem. However, if some items are heavy, they may cause violent banging, or the washing machine out of balance detection may just refuse to allow a spin.
Make sure you fill the drum well. Counter to expectations, the worst violent spins are caused by under-loading - not overloading. Heavy bath mats are notoriously difficult to balance and should ideally be washed with other items or they may gather on one side of the drum. However, some people (understandably) don't want to mix the bath mats in with normal washing. If this is the case and you do get problems with the bath mats getting out of balance I suggest you use old towels or sheets to even the load up. With most modern machines though, a heavy bath mat is more likely to just not get spun rather than be allowed to spin out of control and wreck the machine.
Sometimes you can get an unbalanced load by sheer chance, with loads you have successfully washed many times before. The occasional bad load is inevitable but constant bad loads and violent banging on spin should be looked into. [ Related: loading the washing machine properly ].
Modern washers have built in out of balance protection
Most modern washing machines now electronically monitor the motor during the slow distribution section leading up to the spin. If the load is out of balance, the motor shouldn't be allowed to spin. Typically, a modern washing machine will attempt to balance the load a certain amount of times, or for a certain passage of time, but if it can't, it will either reach the end of the program without spinning, or it will abort spin and turn off. (both scenarios leaving the clothes wet through). Some washing machines may allow a slow spin if the clothes are reasonably balanced, but then unless they settle down, it will not allow a higher spin thus leaving the clothes spun, but much wetter than normal.
Some will indicate a failed spin due to being unable to balance the wash load so check your instruction book to see if your washing machine has this function and what happens if a spin is aborted. Unfortunately some washing machines do not adequately inform the user that it failed to balance the wash load and aborted spin. As an engineer, I have been called out many times because a load was washed but not spun, but there was no fault on the washing machine, just an aborted unbalanced load.
Extra large drums make balancing loads harder
These days you can buy washing machines with much bigger drums. The average drum size was at one time a mere 4.5Kg but is now 6Kg. You can buy washing machines with 7Kg, 8Kg and even 10Kg drums.
These washing machines can be more prone to refusing to spin some small loads because they need even more items to fill the drum. For example, my 7Kg washing machine will not spin 3 large towels. Last week my wife was extremely frustrated with our 7Kg drum washing machine as she had just washed our son's hoody-top and wanted to spin it in the washer. It simply would not spin, so I advised her that it needed something to balance it out. She put in a couple of towels but still no spin. Eventually 5 towels were needed to balance out the absorbent top and allow a spin. This is a minor inconvenience compared to the benefit of being able to fit more washing in (even our king sized quilt) but it highlights how if you have a very large drum it could be more prone to not spinning small loads [ Washing machine won't spin just one item or very small loads ].
I'm loading the washing machine correctly but it still bangs and jumps on spin
This is unfortunately a difficult fault to diagnose. It could be various things including a faulty connection somewhere on the motor or pcb, especially if intermittent. It can be caused by a part overheating, cutting out and then cutting back in causing loss of control. If this fault isn't caused by the loading you really need to get an experienced engineer to look at it. Find a washing machine repairer on Washerhelp
If a brand new washing machine is jumping around on spin
Make sure you have removed all of the transit packaging before using a new washing machine. The transit packaging stops the suspension from working so without the tub being able to bounce up and down on the suspension all the movement created on spin will be translated to side to side movement and the washer will move about and shake.
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