Leyland on the slide!

[Redherring]

I'd be interested to know if anyone has seen this mechanism before? You will notice on the photo of this S-type Leyland c1912 or thereabouts the spring shackles slide along a plate that is fixed to the chassis. A similar mechanism was used on Lacre of the same period. Any thoughts?

 

[Richard Farrant]

I'd be interested to know if anyone has seen this mechanism before? You will notice on the photo of this S-type Leyland c1912 or thereabouts the spring shackles slide along a plate that is fixed to the chassis. A similar mechanism was used on Lacre of the same period. Any thoughts?

 

 

 

Probably was not a good idea, too much friction and wear as it would have to be lubricated which then attacted dirt. The swinging shackle overcomes this. I would imagine this method was short lived.

[nz2]

Halley also had a similar sliding arrangement.

An example in NZ.

Doug.

[Redherring]

Thanks Doug. Now that's the heavy duty version. What really intrigues me is the period this idea surfaced and died. Do you know when the Halley was manufactured? Robert

[nz2]

To date have not been able to locate any numbers upon the chassis to assist in dating. Don't see it often as its over 5 hours away.

Doug

[cosrec]

Although not a slide like that modern day leaf spring trailors have a slpper ended spring that slips inside a cast bracket using the same idea. I have worked on commercials with the same arrangement but cannot think of sort maybe old ford cargo. Only thing stopping axle droping out of cast bracket was a small 5/16 th bolt.

[lynx42 Rick Cove]

The Albion A10 had slippers at both ends of the rear springs for the entire production run starting in 1910 and finishing in 1926. The front spring has the slipper at the rear end only. The slippers are like V blocks so have pressure on many sides.

Of course the Albion A10 was chain driven and that allowed the rear axle to be moved rearwards to take up the slack in the drive chains.

 

The oilers on this, my truck, were all there fortunately.

 

Regards Rick.

[Redherring]

Rick

 

My knowledge of slack chains is limited to chainsaws. How do you maintain rear wheel alignment on the A10?

[N.O.S.]

Chain drives usually have screw threaded adjustable length tie bars. The chassis which started this thread looks like it has sliders at the back end too, but this would leave only the drive shaft tube to take the thrust and alignment - that doesn't seem right, is this the case?

[radiomike7]

Chain drives usually have screw threaded adjustable length tie bars. The chassis which started this thread looks like it has sliders at the back end too, but this would leave only the drive shaft tube to take the thrust and alignment - that doesn't seem right, is this the case?

 

Correct, otherwise there would be an open shaft and not a tube. IIRC Ford E93A Pops had a similar arrangement and in a way so did Constructor front and rear axles by using an 'A' frame in place of the torque tube.

[Redherring]

This question has puzzled me also. If there ever were tie bars or equivalents on this chassis they no longer exist. The alternative, the central drive shaft tube, is a fairly rugged construction and solidly bolted to the forward cross beam. Even so I would have thought it would flex. Maybe this didn't affect matters at 12mph? I will study the chassis again and report back.

[radiomike7]

Not solidly bolted to the crossmember but using a spherical joint to allow movement.

[David Herbert]

If the drive shaft housing acts as a torque tube one would have expected braces from the front of it to near the ends of the axle. Otherwise, if one wheel hits an obstruction there would be massive forces trying to bend the torque tube sideways where it joins the diff.. Also as the ball joint to the cross member is not far in front of the front spring mount, the front half of the spring is doing almost nothing unless the spring is free to rotate around the axle (which it might be).

 

I wonder how long Leyland stayed with this design and if there are any complete vehicles left. Presumably it was inherited from chain drive predecessors where the chain adjustors/tie rods and sliding springs would have worked together well.

 

David

Edited November 28, 2012 by David Herbert

[Redherring]

Does this make sense?...

The spherical joint housing is fixed in position being bolted to the chassis via the cross member. The housing fixes one end of the shaft tube relative to the chassis. The joint allows the rear axle to twist (roll), and also to move up and down (pitch). The question is what happens if one wheel hit a rock there being be a force on one side of the axle tending to yaw the axle? A tie bar is designed to prevent yaw. The question here is a) whether a tie bar existed or b) whether the tube was enough to prevent yaw?

[Redherring]

David,

I will search for evidence of bracing as you suggest. I have seen a couple of photos of this arrangement on very early Leylands. Mike Sutcliffe has told me this scheme was rarely used. I wonder why it was used at all.

[lynx42 Rick Cove]

Rick

 

My knowledge of slack chains is limited to chainsaws. How do you maintain rear wheel alignment on the A10?

 

If you look at my photo you will see that there is a large radius or torque rod behind the chain sprocket back towards the rear axle. Just behind the sprocket an adjuster is visible. You just have to wind the adjuster in or out to tighten the chains.. Ofcourse you have to make sure that the axle is at right angles to the chassis rails. This means that you could have a slacker chain on one side as compared to the other. There are 1/2 link joiners available as well as full link joiners.

 

 

The book says:- "The radius rods also act as torque rods, so that the rear springs are relieved of all duty except that of carrying the load." - "The chains should be taken off for a careful examination about every 1000 miles. They should be tried for stretch; if a half link is to be removed, it should be done. When the chains are satisfactory in this respect, they should be thoroughly washed in paraffin and then steeped for several hours in hot grease, heated until it is thoroughly liquid, to let the grease get properly into the rollers."

 

Hope that this helps explain your query.

 

 

Regards Rick.

[Redherring]

Thanks Rick.

Slippers seem to be a/the(?) practical solution for chain drive vehicles.

Why did Leyland use slippers on this chassis?

Robert

[David Herbert]

Rick,

 

When you posted your photo of your A10 I didn't notice that the 'torque rod' did not go straight to the front of the axle. Is it actually a Vee shape with one leg below the axle and one above it (and the same on the other side of the truck) ? If so how is it possible for one wheel to rise or fall without the other one moving in the same direction ? It would become one giant anti-roll bar.

 

Obviously with chain drive there is no torque on the axle except from braking (which the springs would easily cope with) or are the 'torque rods' just linked to each brake mechanism which is free to turn on the axle itself. That would enable the truck to roll relative to the axle and also both ends of the springs would do equal work which they wouldn't if the whole axle with springs rigidly fixed to it pivots around the front mounting of the torque rods.

 

This last is the same point that I was making about the Leyland axle which pivots around a point only just in front of the front spring mounts. If it were in line with the front spring mounts the axle could go up and down with no deflection at all of the front half of the spring and double the axle deflection on the rear half ! What does everyone else think ?

 

David

[David Herbert]

Just been looking harder at the photo taken from the rear of the Leyland. Just below each rear spring at the height of the centre of the axle is what could be a brass lubricator which would point to the springs being free to rotate on the axle. That gets round the problem that I have been going on about with the front of the spring not doing much.

 

David

[Redherring]

 

A little more on the subject...

Mike Sutcliffe, in the recent Leyland Society Journal, writes... "Another survival... of steam practice was the cast iron dovetailed spring slides. These were quite good and gave a lot less trouble that the early shackles which often broke through "locking" in the brackets." He was writing about the Leyland Y type which was built between March 1905 and 1906. I have studied the Y type chassis pictures at hand and have not seen any form of axle bracing.

The photo above clearly shows the lubricator referred to by David. It also shows the transverse brace that presumably braces the axle against the downwards force of heavy loads. It is a substantial mechanism. I have searched again and there is no equivalent mechanism bracing the axle from yaw.

Robert

[mammoth]

You beat me to it Robert! I have just posted this on our local site, and then came here. This takes the thread a tiny bit further...

 

At first I was wrongly questioning whether Redherring's chassis was a leyland, as conventional hangers appeared in all pictures of the old jiggers, but I have done some scratching around;

In the Leyland Society Journal No14 Mike Sutcliffe writes; "Another survival of the practice was the cast iron dovetailed spring slides. these were quite good and gave a lot less trouble than the early shackles which often broke through 'locking' in the brackets"

It seems that all the Leyland steamers used the sliding spring fixings (fitted under RSJ rails), and that this system carried over to the first production run (class Y, 30 odd built) of petrol trucks between 1905 and 1906. The sliders were at the front only and instead of going under the rails were supported by outriggers fixed to the top of the rails. The next significant class was the X which ran from 1908 to 1912 and this used more conventional hangers fixed to the side of pressed chassis rails.

Now the mystery; The subsequent S class also used conventional hangers but there were some examples which used sliders , and the best picture I have found is in Klappers 'British Lorries 1900-1945' pp 104 with the caption "A 1914 specimen that in 1934 was still running 500 miles a week and with a trailer shifting 10 ton loads". I have not found there to be a correlation between the use of sliders and the joggled frame, as might be expected or bus or lorry use. Maybe Mike Sutcliffe will provide some answers when his history of early Leyland truck gets to the S class.

 

Regarding yawing the torque tube is fixed rigidly to the diff, making a solid 'T', so would be controlling both rotational torque and yawing. The springs would still play a role in controlling lateral movement.

[nz2]

Interesting to note the grease caps and lubrication points for the spring mount to turn on the axle tube. It made me wonder if the pattern was retained of latter models using a similar torque tube. Searching through photos I can only find two photos of the back axle of X model Leylands in NZ. Unfortunately neither photo is from the front showing the grease caps, however it does appear that the springs could well rotate a little on the axle, judging by the shape of the mounts.

Doug

 

[David Herbert]

Good Grief, they did make things hard for themselves on the X type didn't they! As far as I can see Leyland were trying to remove all the vertical bending strain (from the weight of the truck) from the diff housing but still hadn't addressed the forces resulting from hitting an obstruction with one rear wheel, which could potentialy be much bigger. I think that it may have been possible to withdraw the halfshafts and remove the pieces that fill in between the diff case and the giant axle brace and then the whole diff case could be removed as an assy with the truck still standing on its wheels. That is the only reasion that I can see for such an expensive construction. I bet they didn't use it for long.

 

It is hard to make out but I think on this version they have made the brake mounting integral with the spring seat and the whole rotates on the axle. that way the spring is free to take the weight and also deals with the brake reaction torque, which it could easily handle. I wonder what the two lugs are for on the rear of the spring seat just below the spring ?

 

Thanks nz2 for those photos

 

David

[nz2]

After posting the above images,I when out and looked over the Leyland collection. Those same grease cups appear on the 1916, 1919, and 1925 back axles. It is a point I had not released that this section had the ability to turn on the axle housing. I thought it was a manufacturing style and had not related it to the fixed length of the toque tube. This oversight comes from spending too much time about the other end of the truck! (and other projects).

I suspect the two lugs with holes in them about the lower spring mounts could have been for mounting a sprag as a form of brake.

The location though does seem too low to gain a suitable angle to stop a vehicle rolling backwards.

I have seen a few photos of sprags fitted to WW1 vehicles, however wonder when did they stop being fitted onto vehicles?

Doug

[Roy Larkin]

Doug, I'm not sure there is a specific date when sprags stopped being fitted. Although they were part of the subsidy spec, they don't seem to have worked as well in reality as in theory and the lorry tended to roll backwards and over the sprag. I suspect it was a gradual 'forgetting to fit' the sprags as more and more companies discovered their weak spot and nobody seemed too bothered about noticing when sprags weren't fitted.

 

Post war, when Chivers bought several Leylands, they were supplied with the sprags in hessian sacks, which then remained in the workshops awaiting fitting after the bodywork had been built. Those hessian sacks appear to have remained in workshops until the Leylands were eventually scrapped.