Instruments & Switches

[Bensdexta]

I'm starting to think about my instruments.
Below is a pic of my tractor last year before I started rebuilding. I think it's a Nov 61 Dexta (09A...).

My recollection is that the original controls are:
--- A Engine Stop Knob/lever
--- B Starter Isolation Switch/Key
--- C Lights
--- D Heater

In years gone bye I remember the switch B was a contant source of trouble, non-operation due to damp, hence the butchery that is evident in the photo (not sure why there are 4 wires, or maybe it's 3)

I understand that some Dextas (early ones?) have a combined Starter Isolation/Light Switch, leaving C free for a Horn(?), which I don't recall my Dexta ever had? Is this Stefan's set-up for his '59 Dexta, see below (ignore his extra switch box lower left for the purposes of this discussion):


Comments/advice appreciated on the following:
-- Is a horn a legal requirement for operation on the UK public highway? Or is Dex noisy enough anyway?
-- How water-proof/reliable are the combined Light/Isolation Key Switches available today? Why did later Dextas have separate Light/Isolation switches?
-- Suggestions for a reliable, even non-original switch set up, as mine will be a working tractor?
Many thanks,
Ben

[Stefan]

Ben,

early Dexta's were fitted with a combined Isolation/Light Switch, that's correct. So the dash board on my Dexta is restored in the original condition.



If your picture shows an early Dexta, the letters are as followed: A = Stop Lever, B = Isolation/Light Switch, C = Horn Button, D = Heater Switch.

The combined Isolation/Light Switch was not water proof and many switches gave up the ghost. So Ford decided to fit two separate switches, one for the Isolation and one for the Light. The new Light Switches were placed at the same position, means B on your picture. The new Isolation Switch were placed on the right hand side of the dashboard. See picture:


To modified early Dexta's, Ford sent a Service Letter to his dealers. The picture below shows a drawing scanned from the letter. There is to read how to drill the hole into the dash board. And of course, the wirings had to be modified.



I dived very deep into my little Dexta archive and found out, that the first Dexta fitted with separate switches for Light and Isolation had the serial code 09A315817. Good archive ...

New switches water proof?

I hope this was a little help to you.

Stefan

[Bensdexta]

Stefan,
Thanks for the very informative post. [edit see images added below]:


My Dexta is 09A3134xx, so is just prior to the change to a combined isolation/light switch. So looks like my switch positions have been generally messed about before we got her in 1973, with an isolation switch in my Position B and lights moved to Position C, and the horn omitted.

So assuming that I need to fit a horn, I have two options: either reproduce the original layout, as for Stefan's 59 Dexta see above, or modify my panel following Stefan's diagram, to take an isolation switch on the right hand side, like later Dextas below (key just visible):


Can anyone say if the light-only switches are more reliable than the combined isolation/light switches? Or are both types of switches reliable if they are serviced and kept well greased?

What are other folk doing??
Your views appreciated,
Ben

[Jerry Coles]

Hi Ben
If you are more interested in having a working tractor than a restoration then maybe you should be thinking about modern refinements that could make your dexta on the road a safer machine. I'm talking about indicators and brake lights for example.
I rewired my dexta for an alternator installation, indicators, horn, brake lights and trailer socket.
I also included some relays to reduce the wire size going down to the binnacle, extra fuses and in-line connectors to make removal of the binnacle much easier.
I have a powerpoint wiring diagram available which I can send you or anyone else who wants one, just pm me.
Regards

Jerry

[Bensdexta]

I've reverse engineered my old wiring loom and discovered that the "BAT" terminal has been moved from the Light switch where it should be according to the Workshop manual, to the separate "Ignition" switch. The effect of this is that the lights won't come on unless the ignition is switched on. I don't know if this was done intentionally or not.

This has superficial attractions in that it prevents the driver leaving lights on inadvertently or 'fiddlers', eg kids playing with the lights and leaving them on. However I think it's potentially dangerous as if one broke down on the road in poor visibility, one couldn't leave the tractor with lights on to get help, without leaving the key in and ignition on.

Any comments appreciated
Ben

[Bensdexta]

To improve switch reliability I am fitting separate light and 'ignition' switches, with the ignition switch on the right side of the instrument panel as for later standard and Super Ds, see Stefan's diagram above.

After researching available ignition switches, I decided to fit one of these Honeywell Hobbs sealed switches to keep the Welsh rain out:

It is rated at 20Amps, which is more than the usual Lucas type switches used on tractors etc, has a slot shutter and O-rings for damp proofing - claimed to be OK for pressure washing, and has a coded key unlike the Lucas switches that usually use the same key. Needs a 22mm hole in the panel. Available in UK from RS-components for £16+VAT.
There is a US ebay seller selling them for $14 inc delivery --Got to be a bargain
All the best,

[Jerry Coles]

H Bensdexta
Have you the RS components code for that switch.
It looks like the answer to a lot of problems and won't look out of place.
Regards

[Bensdexta]

Have you the RS components code for that switch.
It looks like the answer to a lot of problems and won't look out of place.

Yes this switch comes in various versions. The only version readily available in UK (or even EU) is RS-online pn 515-713. This is the 3 position version OFF, ON, START Honeywell 84829, see http://sensing.honeywell.com/index.cfm/ ... 151666.htm http://content.honeywell.com/sensing/hs ... atkey3.asp

I don't plan to use the spring-loaded START position, I'll just use it as an on/off switch and retain the usual Heater switch. The Honeywell engineer tells me that the switch is rated at 20Amps in the ON position, or indeed in any position so long as the total current doesn't exceed 20A.

There is a 2-position version of this switch Honeywell 84828 but it's not available in Europe. But there's a US guy selling them on ebay for $14 inc US delivery. Some very helpful US forum members offered to act as mailbox and post me a 'gift', but possible delays in Christmas post put me off.

All the best,

[Jerry Coles]

Hi Ben
Thanks for the info.
I was thinking of using it as the switch to control the Starter Solenoid and Heater Relay on my Dexta.
Regards
Jerry

[Bensdexta]

Thanks for the info.
I was thinking of using it as the switch to control the Starter Solenoid and Heater Relay on my Dexta.

Jerry, Should be OK for that; how much current would that be? They wouldn't be ON together. Ben

[Jerry Coles]

Hi Ben
The Starter slenoid should take only a few amps and the Heater Relay (I used a 30amp contact rating) would only draw 1/4 amp so the switch loading will not be excessive.
The advantage of using a relay for the heater is that the heavy wire length is minimised (Solenoid-Relay-Heater) so reducing voltage drop and the heavy wires don't have to go to the binnacle and back.
Regards
Jerry

[Bensdexta]

The Starter slenoid should take only a few amps and the Heater Relay (I used a 30amp contact rating) would only draw 1/4 amp so the switch loading will not be excessive.
The advantage of using a relay for the heater is that the heavy wire length is minimised (Solenoid-Relay-Heater) so reducing voltage drop and the heavy wires don't have to go to the binnacle and back.

No problem - advantages of using relays .
I was surprised to see that virtually all Lucas-type diesel switches (128SA), used on everything from tractors to land-rovers are only rated at 15A for the 'Heater' key position. Do they usually use a Heater relay or does the switch cope because the heater is only on for a few 10's secs?
One might think that arcing from make/breaking the contact would wear the switch over time?
All the best,

[Jerry Coles]

Hi Ben
When I'm next near my Dexta with an ohmeter I'll take a resistance reading of the heater.
I guess Lucas in their infinite wisdom reckon on 15A as Ok for the heater. As I said I'd rather use a relay as its a quick make/break action wheras a switch could be turned slowly and cause arcing of the contacts. I used to use a 36watt soldering iron when repairing Army Radio's and that got plenty hot enough! That would only require 3A if a 12v supply was used, so the heater can't be a much higher wattage. 5a would produce 60W and thats the power of an mains 60w electric light bulb and they get too hot to touch.
Regards
Jerry

[Bensdexta]

Hi Ben, When I'm next near my Dexta with an ohmeter I'll take a resistance reading of the heater.

Jerry, Thanks. That would be very useful. I think the resistance of the heater may increase when it gets hots, so the current would drop a bit. Also think I read somewhere that the heater draws around 20Amps. It would be useful to confirm this.
Al the best,

[Jerry Coles]

Hi Ben
So I left the comfort and warmth of my office and donned my thick winter coveralls (Dickies factory shop sale @ £10.00) and armed with my cheap Hong Kong multimeter, sallied forth to take the measurements.
1st Reading Air Temp 3 Deg C!
2nd Reading Heater resistance 2 Ohms
3rd Reading Heater Current off the scale at 10A (Oh I wish for a good old fashioned AVO meter)
Calculation 1. 12V and 2 Ohm gives 6A or 60W
Calculation 2. 12v and >10A gives >120W
I'm not going out again tonight! and it will be a few days before I have some free time so will investigate deeper later.
Either way 60 or 120W are quite hot!
Regards
Jerry

[Bensdexta]

Calculation 1. 12V and 2 Ohm gives 6A or 60W

Isn't that 72Watts?
I'm unclear why your calculations differ by so much? The 2 Ohms that you measured doesn't jive with your measured current of >10A?
I think I read somwhere that the heater draws around 20A.
Thanks for the mesurements nonetheless - dedication indeed!!
All the best

[Jan 59]

Ben,

After replacing the switch of my 59 Dexta 3 times, replaced it for a Bosch switch nr:0 342 201 009 together with a protection cap.Bosch nr.: 3 346 000 030
When removing the key you can close the opening with the protection cap
These switches were used on the German IH tractors.
Capacity for main lights = 100 Watt.


P.S. These switches are copied by spurious parts manufacturers and wonder what quality you get if you buy there.

Regards Jan.

[Bensdexta]

After replacing the switch of my 59 Dexta 3 times, replaced it for a Bosch switch nr:0 342 201 009 together with a protection cap.Bosch nr.: 3 346 000 030
When removing the key you can close the opening with the protection cap
These switches were used on the German IH tractors.
Capacity for main lights = 100 Watt.

Sounds like a good switch. Have you any more information? I don't think I will have my lights on the ignition switch, otherwise I will not be able to leave tractor with lights on without the key in.
Happy Christmas,

[Jan 59]

Ben,

This switch has 4 positions all with the key.
When you push down the key you open the circuit to the control lights and all other cicuits for starting and preheat.
Turn key first pos. to right parking lights on; second to right dipped main lights; third position to right full main lights.
It is possible to remove the key in first pos. to right what breaks the control circuit,but leaves the parking lights on.
Bosch quotes the max load for the control circuit as 250 Watts what must be sufficient for preheating.
I have this switch in for one year now and works allright.
The total diameter of the switch is 48mm , the mounting hole must be 26.5 mm. I cannot remember if I had to rework the instrument panel, must be my age.

[Bensdexta]

Bosch quotes the max load for the control circuit as 250 Watts what must be sufficient for preheating.

That's 20.8Amps, which is about what the preheater takes, so should be OK.
Happy Christmas,