Lister 5/1 Diesel

Ruston-Hornsby 1ZHR

Rebuilding the Ruston - Page 18


I've been able to do bits and bobs, all of the alternator and cabinet mountings are finished, drilled and bolted, I have the cabling to revise now, so that the heavy battery cables run along the front of the chassis rather than the back.

Got both the batteries on charge yesterday and today, although we make battery chargers, we rarely have anything immediately to hand when we ned one ourselves!

Philip got hold of a neat little 20V 5A variable PSU from Screwfix a few months back, so we both use that for the sealed batteries, knowing that it will keep an accurate voltage and current once set.

Tomorrow we are going to spend the day on the alternator and the battery charging circuits, trying to find out why we are not getting any output. Various theories exist, but the most obvious is that we have a wiring error or a broken cable internally.

The other result we had was finding a complete set of the same meters from a vendor on ebay, plus another set of the same voltages etc but in a more modern format.



Good day!

Sorted out the layout of the battery cables and got those laid onto the chassis, re-terminated the battery end on one of the heavy cables, the other was OK.

Had to remove the flywheel key and move the flywheel out a bit to get the drill behind, but no problems.

Then had a look at the rev-counter belt, which was running 6mm or so out of centre on the pulley, so I knocked up some new spacers for the support stand, and also shortened the belt by a bit to tighten it up a tad.

Once that had been done, it was time to get the volts and amps sorted out! Once we were able to flash the generator field with Philip's little power supply, we started to see some activity on the voltage side.

At more or less nominal rev's, we were getting 33V, and it appeared that the field resistor was back to front, with too much resistance in the circuit between the brushes and the field. Once that was changed round, we had 235V on the output, and a load was quickly organised to try the output compensation field.

We had a 1.5kW radiant heater which was a decent starting load, and we dropped 5V when that went on line. Given that we are probably not trimmed up for optimum output, that's fine, and after a few minutes running it has slightly risen in volts.

Battery charging is going to be fine, there is 36V DC available from the dynamo side of things, and we have to make up a small regulator circuit that will allow charging of the sealed batteries while limiting their maximum voltage.

Lister used a couple of resistors with a link, so that a high or low charge rate should be selected. That was fine for wet batteries, but not suitable for modern sealed batteries.

That leaves the way open to get the cabinet finished off, and the metering and output circuitry wired up. The field resistance was incorrect because we had taken a stab at which end the link should go to, and it was wrong

Once reversed it was away with no problem. The compensation field has a similar resistor, and we'll have to see if that needs a tweak as well. That field boosts the output when a load is connected, by taking some drive off the output cable through a small transformer, the output of which is rectified and fed to the compensation field.



Lots of odds and sods getting sorted out, but not a lot that's worth a picture, until today when we had a couple of bits turn up.

First thing was a flanged spigot and collar from an air conditioning system. This we are going to fit into the cooling tank lid, so that we can fit a chimney to stop the cooling water sloshing out.

It took a while to nibble out and clean up a 200mm hole in the lid, but it fits OK. Drilled some holes for the spigot and then got some primer on both parts. The collar I have left at present.

The other item was a new fuel filter assembly. These are stupidly cheap these days, 15 plus postage for one with a glass water trap and drain. I needed some threaded connectors also, they will be here tomorrow, but in the meantime I got the filter bolted to the frame, ready for piping up.

Before we went to Nuenen, we had an issue with the battery terminals being in close proximity to the inside of the battery cover, and stuck some Paxolin strip inside the lip of the cover as a temporary fix. Now we have made up 2 pces of 1/8" Paxolin to go in there, and have bolted them in.



The meters are almost finished, got a picture of the revised meter after repainting, compared with the original:

Also have the mounting plate back from being powder coated, so couldn't resist putting the meters (duplicate set) in to check that they fitted OK:

Also got the pipe fittings for the fuel filter in the post Friday.


27/06/2010 Continued

Went up to the factory tonight to see about getting the meters calibrated/tested, mainly as they have not be in action for many years and we had them knocking around in a box (as you do)

I set up the 0-30V meter first, as this one needed a new series resistor to make it right. It was originally 0-25V and is now 0-30V.

The original series resistor is 107 ohms. and we added about 28 ohms extra to that to give us the right meter readings. After checking that it was in the ballpark, we got Philip's little power supply with variable voltage and current limit, and had a play.

The results were nicely surprising, the meter held its accuracy over the whole scale, certainly better than 1%, tested at 20V, 15V, 10V and 5V.

I took some pictures to show the comparisons, Philip's PSU meter was checked against our calibrated Fluke III and was within 0.01V, good enough!

Note that these are not moving-coil meters but moving iron, so the current taken to create the magnetic field is quite high, compared with a moving coil instrument. The lower scale on the power supply shows the current being drawn in Amps, 130mA for the 20V setting.

To change the value of the resistor, the whole movement has to be taken out to get inside to the connections. As we are adding resistance, we can do it simply by unsoldering a connection and inserting the extra resistance. Due to the relatively high current, the resistor has to be a wirewound type.

The 30A ammeter will need a new shunt coil making up, the original is copper/brass strip, wound around the former that the movement sits inside.


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