Lister 5/1 Diesel

Ruston-Hornsby 1ZHR

Rebuilding the Ruston - Page 19


Did a bit more on the meters last evening, the 5A ammeter was next, and apart from the scale being revised, nothing else was needed. Using Philip's PSU again, I was able to set the current accurately into the meter and compare the results.

Not quite as accurate as the voltmeter, but pretty close. 0.1A out at 5amps, I can live with that. The 50A ammeter needs a new shunt coil, although it isn't a shunt in the real meaning of the term. It uses 1/2" X 1/16" copper strip wound on edge, 5 turns of which gives the required FSD (Full Scale Deflection)

To bring that down to 30 Amps which we have scaled the meter to, will need something like 3/5ths of the cross-sectional area, so 4mm diameter copper wire will be close. Will have a go at that when I can sort out some wire, have got 3mm but not 4mm, so may be two strands of a smaller size to make it up.

Couple of pictures, first is the 50A shunt coil, as taken out of the meter, and the second is the whole set of meters with the old one behind, or in the case of the first row, alongside.

The 0-300V and 0-30A meters are for the alternator output, the 0-30V and 0-5A are for the battery charging side.



Start of the month, so a quiet period while we get work organised.

Took the ammeter coil former out this morning, and had a play with some winding wire, to see how much we would need to get the 0-30A range that we had scaled the meter for. We had a piece of 4mm coated wire sent down from our transformer people in Stockton, plus we have up to 3mm copper here, including some rectangular strip.

First attempt was way off the mark, and it was only reading 1/2 of what we were pushing through the coil, but after we went down to 2.36mm wire and increased the turns, we got closer, and the third try produced a very creditable accuracy compared with the power supply ammeter.

I'm going to rewind the coil neatly now, and terminate it so it can be fitted into the case, then we will check it again. Being inductive, the position of the rotating armature/vane in the meter movement is fairly critical within the coil, as soon as you start moving the coil a few millimetres away, it starts to drop the reading.



Lots of odds and sods sorted out over the past few days, got the fuel filter plumbed in and fuel up to the injection pump again, gave it a quick spin to make sure it was OK.

Then tackled the control cabinet and getting the meter panel attached to it, so the door could still close without hitting anything. The door catch runs behind the front door return, so enough space had to be left so that the cam could drop behind the return and then rotate.

Easiest thing to do was to space the panel back by 9/16" or about 14mm. There are four existing holes in the flanges for the door hinges, two each side, so they were used.

Next was the holes for the output sockets, they were a bit of a pain as the holes are not exactly just a round hole, but after a bit of punching and filing we got them all done, plus the holes for the output fuses.

We have provided 2 X 240V sockets and 1 X 24V socket. All are outdoor rated BS4343 type, and all are individually fused with a waterproof fuseholder above each one. A 3-pole 20A isolator is fitted, 2 poles for the 240V from the generator and 1 pole for the 24V.

Once that was done, we headed back home for tea!



Had a bit of a head-scratching session this morning, trying to work out the minimum number of wires required to connect the alternator control box to the control panel. Got it down to four:

230V out
Ground (common to both 24V and 230V)
24V Charging line +ve
24V battery +ve

Volt-drop isn't an issue with the 230V, but we do need to check that the charging side doesn't lose too much in the wiring. We have some 5-core 6mm TRS offcuts, one of which will do the job and leave a spare conductor in case we need it in future.

Sorted out a decently-rated variable resistor for the battery charging circuit, it is rated at 11 ohms 5A, just the sort of range that we need, particularly the current rating. Most of our collection of variable resistors are too light to use on more than an amp. Got that mounted in the cabinet, got to punch the cable gland hole in the cabinet gland plate, and then start wiring!

Got all of the internal wiring laid in, had a few issues, mainly on routeing the feeds and getting all the feed connections through their relevant ammeters.

Bit more to do yet, we have allowed 2 metres of 5-core cable to the control box, so we can remotely mount it when the engine is running, to prevent the guts being shaken out of the meter movements.

The 24V socket is more for charging the batteries than anything else, it allows a 10A charger to be connected into the battery circuit.

Browns are the AC Line feed/return for the AC Ammeter, Blues are the AC neutral pickup/combining point for the AC Voltmeter, the two reds are the battery charger ammeter, the connection to the variable resistance is not made yet. Earths will go down to a central stud below the variable resistor. AC neutral is grounded to the alternator frame, as is the 24V -VE.



We are on site for the beginning of this week, putting a new charger and two batter sets (110V) into a substation in Watford, so not a lot of time to play.

Last evening I went back up to the factory and got all the meters finished, including winding a tidy shunt for the 30A ammeter.

Once the coil ends were terminated, the end cover goes on:

Checked that it was still in the accuracy range we wanted, and then put all of them loosely into the panel, just one interference fit problem with a fuseholder, so we will have a look at that tonight.

Because of the rocking and rolling of the engine and trolley, we are going to make it so that the panel can be taken off the mountings are stood on a stand, possibly closer to the viewing public, so have put a 2metre run of cable onto it.


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