What is the advantage of the Rod/lever Series Throttle Linkage?

[NoBeardNoTopKnot]

I best 'fess up. In all the years I've owned Series LRs, all have had cable-op throttles. I inherited my 109, its cable-op works and I know no different. Either my grandfather or father converted long since.

 I looked at the stock set-up recently, I'm a simple soul, hence I'm baffled?

Back when, was that just how it was done? In the context of a bowden-cable, what's the reason for such a complicated solution. Yes, fine...  it's a solution. Only it takes up space, more parts, and must have burned more labour to assemble, it's prone to slop, and more costly in production.

Yes, yes,  some of you have had yours for forty years and will report no problems, "it's a time-served design" etc only that's not the question. I can see why LR spec'ed cable-op on 1980s coilers. I can't see why LR chose a linkage in the first? Were other vehicles from the era with a linkage too, and if it is preferable, shurly-shirly the choke-cable should be linkage-op too?

Why was it ever a linkage, where is the advantage, what am I missing here?

[Wittsend]

KISS

Keep it simple ...

Cable operation does have some advantages, but you could be in trouble when the cable snaps.
More so if a PO has used some sort of "home brew" bodge - where did the parts come from



 

[Peter Holden]

Disadvantage of rods off road is trying to keep the rdvs steady as the engine  bounces on its mountings but it isn't a big problem.

Cable, wel the S3 diesel into mine has a cable but it works backwards way round, the inner is fixed and the outer moves making a simple system unnecessarily complicated  but it is one step up from the bodge that it came with that caused a wet foot every time it rained

Peter

[GlenAnderson]

I think a combination of factors, but mainly longevity and reliability in service. Rod linkages followed the convention of the time that the vehicles were first designed and built. Rover was a quality car manufacturer and engineering pioneer in the 1940s and 50s, and the Series 1 and Series 2 had linkages that were miniature works of art. Threaded rods, ball and socket joints that could be lubricated, minimal backlash and reliability that would match or outlast the design life of the vehicle.

As the management changes of the 1960s and 70s introduced cost cutting, those linkages were cheapened by replacing the expensive joints with bits of bent wire and clips. These were reliable enough initially, but don't have anything like the lifespan.

As a way of connecting two levers, a Bowden cable is a fine solution, but it becomes a consumable item with a finite life. Personally, I would prefer to have the control and feedback a cable offers, and accept that I would have to carry a spare on an expedition; but Rover's engineers obviously felt that they'd sooner engineer something that was less likely to break.

British Leyland's engineers were tasked with saving money, but without the freedom to redesign a better cheaper solution.

[Theshed]

My first Series had linkages, my current has a mixture, having been converted from Petrol to Diesel.
Age is not always a factor in longevity. Many years back, driving a late 80's Merc van, a couple of years old at the time, one of the linkages came off.
Lane 2 M6, approaching Windy Hill, just before the hard shoulder ran out ! That was, well interesting ?
Luckily enough I had the Series at the time so was familiar with this system. Pop open the engine cover, clip back into place and away I went, carefully.
All without leaving my dry, warm cab.   

[NoBeardNoTopKnot]

I suspect Glen has it, or is not a mile off. The answer is cultural, when the Series LR was still in the drawing-office, the design-engineers were of the generation with a hand in rod-operated brakes and pre-war design. The design is a hang-over from that mindset, and went on because, well... it works. There's not actually anything WRONG with it, far from it, so why argue? And that was that.

Let the moss grow... It would take a complete design-revision to shift. Hence - rightly or wrongly - it, and much like it survived; probably for far longer than it should.

[biloxi]

Having rods probably made it easier to connect governors, governor quadrants, hand throttle quadrants etc.
I really haven't got a clue, just guessing.
.W.

[NoBeardNoTopKnot]

Nah, if my experience of design practice has much credence, whilst valid then, the thought process back when where:

Threaded rods, ball and socket joints that could be lubricated, minimal backlash and reliability that would match or outlast the design life of the vehicle.

...would see today's design-engineer made a laughing-stock, and then shown the door. This for blatant disregard for why he has the job in the first place.

[Alan Drover]

The rod accelerator linkage on an Aston Martin DB2/4 is an engineering work of art. I had to dismantle one when I was helping remove the engine some time ago. Every junction has an adjustable ball joint.

[Exile]

Having rods probably made it easier to connect governors, governor quadrants, hand throttle quadrants etc.

That makes a lot of sense to me.

[William]

The original Auto Test report on the series 3 notes, in this respect:

'The design of the accelerator is very cunning indeed, enabling the driver to maintain something like a constant throttle opening even when the vehicle is being thrown about over really rough ground.'

So maybe the rod linkage is designed to iron out some of the shock that you'd get from a more direct cable linkage?

[biloxi]

To me that sounds more like a desperate excuse than a reasonable explanation.
.W.

[NoBeardNoTopKnot]

To me that sounds more like a desperate excuse than a reasonable explanation.
.W.

Nay, it's a cute bit of waffle to hide the piffle.

[w3526602]

Hi,

I have often cobbled my own cables, for all sorts of vehicles, using bicycle inners and outers  ... gear cables for throttles, brake cable for heavier stuff, from Halfords.

The biggest problem is cutting the inners to length. The "wire" de-laminates when cut, so needs soldering before cutting. Mum had a gas oven, so heating a big soldering iron was easy. I now only have a small electric soldering iron.

I'm guessing that Raleigh, Hercules, etc, can contract out the supply of bike cables, but less sure about the ball coupling thingies for Land Rovers.

Reference the rod linkages, I usually "fine tune" the length of the rods by adroit bending over my knee, but that requires having a supply of second-hand rods.

One solution that comes to mind, but never tried ... stockholders can supply "threaded bar" in short lengths, by mail order (if anybody can tell us the thread pattern for throttle linkages?) The disadvantage is the appearance of having "fully threaded" link rods. Perhaps they could be sleeved with screen washer hose?

OT ... unless you are clever ... there is something in my mind about a car produced in the 1960s (possibly very EARLY Hillman Imps) having pneumatic throttle linkage. I have no idea how it worked, but suspect it was provoked by the needs of the rear mounted engine ... several cubits of inner and outer cable running under the floor introducing the matter of friction.

602

[stevesharpe]

I do concur that the linkage design is absolutely crackers, even though LHD was probably a bit simpler

However, isn't this part of the charm? The same applies to leaf springs and carburettors-no one would have them now.

I plan to keep mine but I might fit the ball jointed rods you can buy on eBay for £15 or so to remove the slop

Steve