Issue 37 Unmanned Systems Technology April/May 2021 Einride next-gen Pod l Battery technology l Dive Technologies AUV-Kit l UGVs insight l Vanguard EFI/ETC vee twins l Icarus Swarms l Transponders l Sonobot 5 l IDEX 2021 report

67 every 100 hours depending on the operating environment. The main oil pump is a gerotor-type system bolted onto the crankcase cover, just below the crankshaft’s power take-off (PTO). It has an automotive-type funnel beneath it to draw oil up through a screen, and a pressure regulator is also integrated to maintain oil pressure across the operating speeds of the engine. Oil is directed through drilled passages in the cast engine parts to reach the areas that need constant lubrication, although it is worth noting that the PTO end of the crank on the 23 bhp engine does not technically fall into this category, as a pair of ball roller bearings are installed between the crankcase cover and the front crank end. “On the vertical-shaft versions of the engine, we use a plain bearing at the PTO, in which case we drill a passage to deliver oil there.” Bruener says. In the 23 bhp engine, the oil runs from the pump, through initial passages in the crankcase cover, into the side walls of the crankcase, then through to the flywheel side’s plain bearing. From there, two more drilled passages lead the oil up to the camshaft and the crank pin (running through the crankshaft). The movements and contacts at these last two locations distribute sufficient oil to the con rods’ big and small ends, as well as to the pistons and rocker arms. “Once operation starts there’s really no wear at all, and we rotate the engines before we set the lash so that no particles of dust or grit can get between the balls and sockets of the pushrods and tappets,” says Duch. “Once the valve lash is set it’ll run a really long time before it needs to be adjusted again – typically 250 hours but it could be much longer depending on the environment.” On the 40 bhp engine, the oil is initially split to run 50-50 between the crankcase’s PTO side (where two steel-backed bushings sit) and the flywheel side (where one steel-backed bushing sits). At the PTO end, the oil runs through a drilled cross-hole in the crankshaft to reach the crank pin and con rods. The flywheel end’s oil splashes to reach the camshaft and valvetrain before being collected in a sump for delivery back to the pump. “There are two bearings at the PTO end of the crank on the 40 bhp engine,” Duch says. “On both engines there’s a high- grade ethyl polyacrylate ring just beyond the bearings to seal in the oil. “There’s a similar seal just past the flywheel’s bearing, and a pump down at the bottom of the crankcase on the horizontal shaft engines. So these various systems all ensure that the oil is collected and delivered back to the main filter and pump without any losses.” For the most part, the oil circulation components are standard off-the-shelf, although Duch adds that a high-quality check valve has been selected for the filter, to prevent back-leakages and distortions if the oil runs slightly hotter than usual. Each piston has three rings, configured for standard shapes and functions. The top is a barrel-face iron ring with a flash chrome plating, the middle is a Unmanned Systems Technology | April/May 2021 23 bhp Vanguard Small Block EFI/ETC engine Vee twin Weight: 35 kg Bore and stroke: 75.5 x 70 mm = 627 cc Gasoline Spark ignited EFI/ETC Naturally aspirated Air-cooled Throttle body injected Maximum power: 23 bhp (at 3600 rpm) Redline: 4200 rpm Compression ratio: 8.3:1 Some key suppliers ECU: Mahle Ignition coils: Mahle Voltage regulator: Mahle or Trombetta Fuel pump: Delphi TMAP sensor: Delphi Fuel injector: Aisan Gaskets: KBK and ISS Die-casting: in-house Crankcase: in-house 2D simulations: Gamma Technologies 40 bhp Vanguard Big Block EFI/ETC engine Vee twin Weight: 56.7 kg Bore and stroke: 85.5 x 86.5 mm = 993 cc Gasoline Spark ignited EFI/ETC Naturally aspirated Air-cooled Port injected Maximum rated power: 40 bhp (at 3600 rpm) Redline: 4600 rpm Compression ratio: 8.5:1 Some key suppliers ECU: Vitesco Ignition coils: Fenix Voltage regulator: Trombetta Fuel pump: Delphi TMAP sensor: Delphi Fuel injector: Delphi Gaskets: KBK Die-casting: in-house Crankcase: in-house 2D simulations: Gamma Technologies Specifications