Thread: Helical Gear Cutter required.

I gather the price of gear cutting would vary widely depending on several factors. As for many types of jobs a similar setup cost is involved for a one off as for a batch. Also design work may be costly. Probably considerably cheaper if a blueprint or sample of the gear required can be supplied provided critical dimensions can be readily measured -ie wear and /or damage not making this difficult /impossible.

You could ask Joe Cottam at Berrigan for a quote. See www.cottamengineering.com.au About 18 months ago he designed and made for me a special input gear to replace the standard one in an LT230 Transfer Box with 1.003.1 High range. (Serial number indicates it originally was in an early Rangie with torque flite auto.)

The 26 tooth standard input gear drives the 41 tooth middle gear on the intermediate cluster. The high range gear on the cluster in 1.003 boxes is slightly larger diameter and has 44 teeth. I did some looking thinking and measuring. Concluded that a 22 tooth gear could be made to drive this - similar to how the input gear drives high gear in series transfer boxes except back to front. Anyway, Joe Cottam designed and made one. Heat treated it too. Did not bother including the PTO dogs on the rear which would cost considerably more using the cutting equipment he has and I am very unlikely to want anyway. Seems that now Joe has recorded the measurements, he could make another one off of the same thing cheaper. For larger quantities, the price per unit would drop again.

The overall result is LT230 with 1.27:1 high and 4.21:1 low range. Expensive one off gear but most likely cheaper than installing 4.7:1 diffs with 1.003 transfer box or one from a disco with Maxidrive 30% extra reduction low to achieve a similar result. I have yet to find time to reassemble this box with new gear and instal it in my 300TDi defender 130. Hopefully soon. One job for mate who will be staying here for a while is to take appropriate photos that can be posted on line.

For my purposes with a Defender, I reckon slightly faster high range and slower low would be an improvement. The 1.003 box with standard diff ratios would obviously have high first and reverse too fast.

Thanks mox.

The task I have in mind is cutting the mainshaft gear count and profile for a Series Forward Control/1 Ton all helical box into a blank output shaft for a Roverdrive. I can supply an original NOS gear and its mating intermediate cluster.

This way I can leave the original low ratio transmission in an ex-military SIIB and travel to ex-military events like Corowa at speeds faster than 70KPH. It would be a shame to mutilate a vehicle that has survived 37 years mechanically unmolested with only 15,000Km on the clock.

Diana

Is Joe Cottam, the guy with the modified Meteor tank engine powered tractor?

Originally Posted by Lotz-A-Landies

Thanks mox.

The task I have in mind is cutting the mainshaft gear count and profile for a Series Forward Control/1 Ton all helical box into a blank output shaft for a Roverdrive. I can supply an original NOS gear and its mating intermediate cluster.

This way I can leave the original low ratio transmission in an ex-military SIIB and travel to ex-military events like Corowa at speeds faster than 70KPH. It would be a shame to mutilate a vehicle that has survived 37 years mechanically unmolested with only 15,000Km on the clock.

Diana

Is Joe Cottam, the guy with the modified Meteor tank engine powered tractor?

Appears to me that you want to instal a Roverdrive but they do not make a version that will bolt straight in to a Series 1 ton transfer box as mainshaft gear is different. So you need to get one cut to suit. Regarding the gear I got cut to convert 1.003 /3.32 ratio LT230 to 1.27 /4.21, if I ever have the inclination and money, could get another gear with the same teeth but to fit an LT230 type Roverdrive made.

Looks like your job does not involve much design work compared with mine. Presumably basically copying the teeth of the one ton mainshaft and the rest of the part required should be the same as for the Roverdrive one to fit into a standard transfer box.

Am not sure whether the part you want would need to be made from scratch. Possibly a small company like Roverdrive may be willing to supply a part machined to standard dimensions as far as practicable except for the gear. They most likely would not want to make a complete one off rare one, especially without having all surrounding components on hand to make sure it fits and works.
I also wonder regarding the NOS mainshaft gear you have if a feasable and cheaper option instead of cutting a complete new gear could be turning out the middle with very hard cutting tools or first softening it in the heat treatment oven. Then somehow securing it over what presumably is a modified hollow shaft - the Roverdrive output shaft.

Yes, Joe Cottam is the bloke with the modified Meteor tank engine I gather purchased from the bloke who bought all the Australian Army's Centurion tanks and spare parts. The Meteor is a derated Rolls Royce Merlin, which could possibly be described as the main aircraft motor which won the Second World War. Was used in Mustang and Spitfire fighters and Wellington, Lancaster and Lincoln bombers and presumably other planes. From memory details are water cooled V12, 4 valves and 2 spark plugs per cylinder, displacement 27 litres or 1650 cubic inches, 5.4 inch bore, 6 inch stroke. Think original aircraft version of 1936 was 1,030 horsepower but gather later some later ones made by Rolls Royce at Derby produced up to 2,700 running at something like 3,000 rpm - fast considering the long stroke and 15 psi boost - from turbosupercharger that ran at up to 30,000 revs. Two bearings on shaft but had oil pump and also scavenger pump that retrieved oil from wherever G forces pushed it - both driven by worm drives. . Apparently at the time, Yanks could not believe how RR built Merlins to such fine tolerances and their versions often blew up much sooner when abused. However bullet hole in radiator would soon stop any water cooled motor.
I gather some Merlins were built in Australia too.

Re "Riverina Screamer", tractor pull tractor built and owned by Joe Cottam of Berrigan NSW: Motor was originally Meteor out of Centurion tank, for which I gather rated horsepower was 650. However early modifications for it included Merlin pistons and camshafts. As they are one of the aircraft motors that runs the opposite way to automotive ones, diff needed turning over to compensate. An apparent initial problem was no Merlin water pump available, which were effectively the same as Meteor ones but are run in the opposite direction. Solution: Direct shaft drive replaced with chain from electric motor. Also electric fans on radiator - one of two from Centurion tank. For tractor pull purposes, this is a good system. Once forward movement ceases and rear wheels are simply throwing dirt everywhere, no problem switching off motor running at full power without idling it down if water pump and fans keep going to dissipate heat.

Instead of the Merlin blower, Riverina Screamer has a turbocharger each side. Two big exhaust pipes and two small ones from the wastegates. It actually makes less noise than its local super modified opposition which both also have 24 exhaust valves with straight pipes out of each. One has V12 Allison and other three Chev V8's in series. Note it is a good idea if attending tractor pull to take ear muffs!

I have heard and forgotten several more modifications done to this motor. One thing that it took a long time to get right was the fuel injection.
Then next problem behind motor is no standard clutches will take the power. Recall that one built to suit incorporates components from traction clutch of Caterpillar crawler.

Of course as for other motor sports, the skill of the driver, some luck and fine tuning the whole machine so it can hopefully perform better that ones the oppositions have is the objective. In this case to pull a sled the furtherest. As it is travels along the track, weights move from over the wheels at the back to over skids at the front. The load gets progressively heavier until tractor motor stalls or it loses traction. That is if something has not already gone wrong eg motor stopped, something else busted or tractor run off side of track. They are not necessarily easy to steer straight when rear wheels are spinning.

Any competent machinist with a universal mill, dividing head, tailstock, gear train, and the appropriate cutter can cut a helical gear.

Get some machine shops out of the Yellow Pages. Hourly rates are something shocking these days. A mate still in the business says he is cheap at $120 per hour, minimum invoice $95, and $60 for a quote.

Originally Posted by mox

...........
Yes, Joe Cottam is the bloke with the modified Meteor tank engine I gather purchased from the bloke who bought all the Australian Army's Centurion tanks and spare parts. The Meteor is a derated Rolls Royce Merlin, which could possibly be described as the main aircraft motor which won the Second World War. Was used in Mustang and Spitfire fighters and Wellington, Lancaster and Lincoln bombers and presumably other planes. From memory details are water cooled V12, 4 valves and 2 spark plugs per cylinder, displacement 27 litres or 1650 cubic inches, 5.4 inch bore, 6 inch stroke. Think original aircraft version of 1936 was 1,030 horsepower but gather later some later ones made by Rolls Royce at Derby produced up to 2,700 running at something like 3,000 rpm - fast considering the long stroke and 15 psi boost - from turbosupercharger that ran at up to 30,000 revs. Two bearings on shaft but had oil pump and also scavenger pump that retrieved oil from wherever G forces pushed it - both driven by worm drives. . Apparently at the time, Yanks could not believe how RR built Merlins to such fine tolerances and their versions often blew up much sooner when abused. However bullet hole in radiator would soon stop any water cooled motor.
I gather some Merlins were built in Australia too.

...........

The Merlin was developed as a follow-on to the Rolls Royce R racing engine of 1929 (which produced 2500hp at 3200rpm from 37l, but needed a lot of development to get it to keep going for the length of a race!), or perhaps more accurately an enlargement of the 1927 Kestrel using the lessons of the R.

Merlins were used in a wide variety of aircraft in addition to the ones you mention, including, for example, Hurricane and Mosquito, as well as the civilian Lancastrian and Canadair airliners. Best known, however as the power plant for Spitfire, Hurricane, Mosquito, Lancaster and Mustang. It was supposed to be superseded by the larger capacity Griffon engine, designed to the same external dimensions, but the Merlin development kept increasing power so that it was close to the end of the war before the Griffon actually was used.

The main reason for the superiority of the Merlin over competing engines was Rolls Royce's expertise in supercharger design, and their willingness to use boost to increase power - most aero engines up to then used supercharging only to compensate for altitude and induction losses. And they were gear driven centrifugal blowers, not turbosuperchargers, in some models with two speed gearing.

As well as UK production a modified version of the engine was built by Packard in the USA - I think they used US threads and were modified for available production methods. Late in the war production of the Merlin started in Sydney at CAC (my father worked there at the time as a toolmaker) for use initially in Australian built Mosquitoes, and later Mustangs and Lincolns.

As stated the Meteor was a tank engine based on the Merlin, and according to some sources using at least in part, blocks and some other components that failed QC for air use. Accessories were quite different.

John

Some Landy enthusiasts will be interested to know that the Land Rover, Lode Lane factory was built as a shadow factory for building Rolls Royce Meteor tank engines during WWII.

Originally Posted by Lotz-A-Landies

Some Landy enthusiasts will be interested to know that the Land Rover, Lode Lane factory was built as a shadow factory for building Rolls Royce Meteor tank engines during WWII.

Rover actually did a deal with Rolls Royce, exchanging Rover's gas turbine development business for RR's tank engine business. I am not sure that Lode Lane only built Meteors, I suspect it also built a lot of other wartime items. The factory was given to Rover after the war, as a thank you for running it during the war. Rover's original factory in Solihull was somewhat the worse for wear after attention by the Luftwaffe.

John

Hi Diana.
I am sure you know the differences between the boxes and how it will affect your overdrive. I am posting pics of the different PTO,s so others will know. The short PTO on left is the Helical one.
Didiman