LZ 280 Belt replacement home
 
 
General

In order to inspect the oilbath I removed the oilbath cover. (it was easy with my old lathe) But this one was stuck, and after applying a little force it came off tearing apart the oilseal. I don't know why it was stuck, maybe it was due to old fat or glue/sealant from an earlier maintenance job.

In order to replace the seal, the headstock spindle has to be removed. This was good opportunity to replace the belts also. The belts had a little "wobble" due to a long period in which the lathe was not used. The belts were probably comprimated at the contact point with the pullys. It was also a good opportunity to inspect the rollerbearing from the backgear-unit.

Step 1 - preparing the main spindle

Slacken the nuts from the bronze bearing at the left innerside

Remove the cap at the backed of the spindle at the left outerside

Slacken the nuts of the main bearing on the right innerside

Remove the cap that holds the main spindle bearing on the right outerside

The seegering close to the uttermost left gear has to be taken out of his groove.

Two pieces of wood have to be inserted to give a contraforce to the primary bullgear of the backgear train. The elastical cords keep the blocks in place

 

 

Step 2 - removing the main spindle

Tap the back of the main spindle. I used some wood blocks but they could not quite stand the blowing forces of the hammer. For the last blows I used a piece of bronze (this was due to the bullgear at the right, this has a very tight fit around the spindle.

Put a rod inside the spindle, this will catch the loose parts and prevent them form falling inside the housing. (I used a black tube as can be seen in the left of the picture)

Carefully take each part off the rod and rember (write down) their place in the following order and which way they where mounted.

The V-belt is prevented from being removed by the second spindle of the backgeartrain. Step three shows how this is to be removed.

This is the mainspindle. At the right side the mainspindle bearings stay in place.

Step 3 - backgear axis disassembling

   

Turn the backgearselector in the upright position. Then remove the handle knob. And the ring.

First remove the cap that holds the frontbearing of the shaft.
Withdraw the handle shaft as far as possible
Drive the shaft out with a few gentle blows against a piece of wood.
Take the backgearshaft out.

Step 4 - variatorpully disassembling

Number the caps and bearingholders that come off.
Step 5 - reassembling
I replaced the roller bearing with a closed type. They only do 6000 rpm instead off 10000 rpm off the open type. But the lathe does only 1600 rpm so its quite sufficient.  

Take great care off the alignment of the splines and the keyways. Also take care of the oilsplash shimring near the backend bearing.

The resetteling of the bull-gear takes quite a bit of force. In order to guide the blowstrokes around the gears there need to be some pieces of wood that support the pully. I used metalpieces, they deform the rim of the headstock.

 
Step 6 - finished
Here's the headstock completely reassembled
The variator belts are sized as the prescription in the manual. But it seems to me that the size is to wide.
Here can be seen that the belt is running above the top of the pully in close up.