STABILIZE MOTOR ON ELECTROLUX Z355 CYLINDER CLEANER

[CarlH]

I didn't get any assistance on my earlier question on how to remove the rear housing (clear plastic moulding) behind the motor, but managed to do it.

The motor works fine, but had been twisting on its mountings and had pulled one of the supply cables off the connector to one of the field coils. The two supply cables were TIGHTLY WOUND ROUND the spring which is compressed between the back of the centre of the motor and the housing to form the back motor mounting The pull might have broken one of the cables and, in this unearthed ("double insulated"!!) appliance, caused the steel case to go live (!!!). Instead, the result was far less worrying, but its cause does need eliminating.

Why did this happen? Because the fins moulded into the inside of the housing, which interlock with fins on the back of the motor to prevent this twisting round on its axially central front and rear central mounting points, had failed.

Why this failure? Because this motor, which is a replacement fitted about 15 years ago, is nearly 50% more powerful (1,150 Watts) than the original (770 Watts). This gave a huge improvement in sucton, but no doubt the housing fins had been gradually bending and eventually breaking off ever since the change. Finally, enough of them broke to allow the motor to turn round several times - with the results already described.

I am in a quandary - for two reasons - and seek guidance:-

1. I can't find a new replacement housing, though it is rumoured that it can be got. Does anyone know from WHERE?

2. Even if I could find one, sooner or later the very high starting torque reaction will again overstress the housing fins. Possibly this might take another 15 years, by when this cleaner is most unlikely to be still in use! However, if a new housing is fitted, it would make sense to fit a SOFT START module - to stop the motor jumping up to full revs so quickly and exerting such a shock loading on those fins.

Any ideas? There is not exactly masses of space inside, as anyone who has done serious servicing on the series of Electrolux cylinder cleaners to which ours belongs will know.

 

[assuhors]

The part number for the Motor Suspension Bracket is Electrolux 322860008,don't think you will find one though.

 

[CarlH]

So Electrolux call a large domed plastic housing a "bracket"! Well, I do realise that there are many strange names for parts for which much more obviously descriptive names seem more appropriate.

However, many thanks for going to the trouble to reply and try to help me.

If the "bracket" is now unavailable (which wouldn't surprise me, given the machine's age), can something else be rigged up to prevent torque reaction making the whole motor twist? (It can go round and round when it starts after the interlock fins have failed, but the cables break eventually, and it then does stop!)

I had wondered about inserting two pieces of steel tube across the inside of the casing, the distance between them being the same as the distance across the two opposite flat sides of the protruding section of the motor's laminated field cores. These tubes could be tight enough against the cores to prevent the motor making any attempt to turn on its mountings when it starts.

What worries me about this idea is that a short might occur in the motor and make the field core coils live. The machine is electrically of that so-called "double insulated" design, so has no connection to the domestic installation's protective earthing through the 13 Amp plug (the flex is 2-core). So a short within the motor, making the field coil cores live, or to the steel case (bare metal inside), or to anything connected to the case, would not trip the MCB/blow the fuse for the circuit supplying the 13 Amp socket. The outside of the machine's case is covered in padded leathercloth. That might offer some protection against electrocution. But my proposed motor stabilising tubes would pass through the sides of the case, and would be in electrical contact with it as well as with the motor field coil cores. The nuts holding these tubes in place would be on the outside of the case and very difficult to insulate effectively.

Add an earth connection and change the flex to 3-core?

Problems with this idea:-

1. The spring return cable storage reel might not work with larger gauge flex. At the very least, the flex would have to be considerably shorter as there would be less length capacity on the reel for it. And while the original flex is of a good length, you would not really want it any shorter.

2. Contact between the output terminals of the rotating flex storage reel and the the motor input terminals is via slip rings, of which there are two (line and neutral). The storage reel, with the spring loaded contact terminals for the slip rings, is in the detachable plastic rear end of the machine (where the two wheels are). An earth connection would have to be bonded to the machine's case, so would add to the difficulties of dismantling for service etc.

All in all, a stabiliser made from an electrically insulating material (as is the case with the original "bracket"/moulded clear plastic rear support housing for the motor) would be vastly preferable.

Any other thoughts/guidance? I have a sinking feeling that this machine is now beyond resuscitation - at a mere 30 years of age!