People visiting us regularly in the workshop don’t see big changes on the tractor and come to the point where they ask what we are doing all the time, since the tractor is basically ready …
All the major components are painted and back on the frame, engine, turbochargers, rear axle, … . So, we should be good to start it up an take it to the first pull. But it’s missing a lot of the small details, which are mainly related to connecting everything together. Time to get you a small insight, what has to be interconnected on such a machine:
The engine needs to be connected to the rear wheels through drive shafts. No U-joints allowed, so everything has to be perfectly aligned and will be connected with splined shafts and couplers accordingly. Since you can’t buy these of the shelf, they need to be machined. They have to take all the horsepower and you can’t just do them out of normal steel, so you need to find an appropriate material. The solution comes in the form of tool steel with the desired hardness and flexibility at the same time. The disadvantage of tool steel is, that you will have a hard time to machine it. Lots of researches and tips from other competitors lead us to a type of steel which comes in a normalized form, thus is easy to machine and will get it’s final mechanical characteristics in a specific hardening process.
Time to machine the outside and inside splines …
Each spline has to be cut individually, indexing the splines has a zero-error-tolerance and you often need to take several passes to come to your final dimensions and have a perfect fit … time consuming and you have a lot of time to think about all the other work in front of you to get the tractor done 😛
… all major drive line parts are finished and on their way to a specialized company for hardening. Finding a company which can and will harden the parts to the needed specifications in our area is a whole other story
… still missing the long drive shaft between the clutch and gearbox. It needs some final touches on the gearbox (good topic for another episode 😉 ), to get final dimensions. It will anyways be machined out of another material, since there is no way (at our hands) to harden such a long piece without a tremendous amount of deformation.
In parallel we are making all the fluid and gas connections. Let’s try to list all the needed gas (air, exhaust, breathers, …) connections, starting with the trivial ones:
- Intake air to the turbochargers … easy, since there is just an opening to free air … well, NO. We need to run an air restrictor in our class and ETPC rules call for an intake protection (I think, I will cover all the safety stuff in a separate episode).
- Exhaust gasses to free air … no problem neither, just a big pipe with an elbow and you are done … well, NO. There a rules for your exhaust pipes and further safety elements behind the turbos.
- Compressed air goes from the turbochargers into the engine … sounds easy, some pipe, rubber hose and clamps … well, NO. In our case we didn’t want to go with full custom made intake manifolds from the beginning, so we modified the stock aluminum intake manifolds, welded some pipes and elbows to it and were good to go. Besides this, the connection between the turbos and the engine had to incorporate the following elements: throttle bodies, blow-off valves, holes (actually it was a little more complicated) for the fuel injectors, connections for temperature and pressure sensors, ports for vacuum connections (other elements of the engine management system need these), … I certainly missed some others 😉
Exhaust manifolds from the engine to the turbochargers … sounds easy and needs just hours of work in stainless steel … cutting, welding, grinding an press forming adapters from a specific round to a specific rectangular shape
… at some point you need to integrate connections to be able to disassemble your construction 😛 V-band connections are great for this purpose
- The turbo chargers, due to their basic function principle with hydrodynamic bearings (the shaft spins and is centered in a pressurized oil layer in the bearings) need their own oil supply and return, which we realize with a dedicated oil pump, filter and a separate oil tank for the turbos.
- All tanks, in fact circuits with liquids, need a ventilation with a receptacle to catch any liquid exiting the ventilation and avoid contamination of the environment. Counting all these gives a nice number as well: rear axle, rear planetaries, gearbox, two braking circuits, hydraulic steering, fuel tank, turbo oil tank, crankcase ventilation, …
- Hydraulic steering and brake systems … I’ll cover these and their function in a separate episode with the other controls of the tractor (clutch, throttles, shut-offs, …)
- As we switched the engine lubrication system to an external oil pump, oil needs to go from the crankcase to the oil pump and from the oil pump into the engine … easy … well, NO. Connections were welded into the oil pan, after the oil pan was shortened and thus allow the oil feed to the two stage oil pump.
Actually they are not just pipes welded to the oil pan, but inside they are routed to the deepest point of the pan, incorporating filtering elements to avoid pump damage … hard to get a picture of it now
Not using the original oil pump left us with the question how to get the oil into the engine. We ended up feeding the oil directly into the main oil galleries of the engine. Oil supply in an engine is just a work of art, when you consider that all the complete internal oil supplies can’t be cast with the engine block, but are machined and drilled afterwards.
Not using lots of the stock oil supply, we ended up without an oil filter and oil pressure regulator. The solution came in machining an oil filter according to our needs, integrating an adjustable pressure regulator with a return line into the crankcase. We integrated another feature, which is a transparent plate, in the filter, allowing us to inspect our filter element without the need to open the filter. This allows for a quick check on engine health between runs and eventually call it quit before a major engine damage.
Most of the hose connections are done with AN-fittings (Dash-fittings or whatever you are used to call them). This is an amazing system, common in motorsports, which allows you the realization of virtually any connection without the need of press fittings. Well, nearly any connections, besides those which are non-standard or you just forgot to order the correct ones … let’s just machine them
With all the connections, the front of the engine becomes really cramped
- Then comes all the fuel stuff … fuel pump, fuel filter, fuel pressure regulator, fuel distribution, and fuel rails. I’ll try to cover this in a dedicated series of episodes on engine management.
What did I miss? … Aaah, all the electrical stuff
I think, one gets a pretty good overview what was and is ongoing in the workshop, without seeing major changes in the state of the tractor.
Talking about liquids, some of them have their containers, trough the way how they are constructed, as the engine oil or the rear axle oil, others need to have their containers build. With not a lot of space left on the front, due to overall vehicle length, time for old-school cardboard models 😉