Well, I'm not really as far along as I had hoped / thought. The arrangement for the small electric motor that runs the hydraulic pump does not look satisfactory. Does anybody have any helpful suggestions?
Background: I'm converting a 1970 Citroen ID. It has a manual transmission, but hydraulic suspension, power steering and power brakes. The hydraulic stuff runs off a 7-piston pump that was turned by a v-belt from the camshaft. It functions well at ~500 rpm. The pressure regulator has a small reservoir; when pressure is sufficient (~2500 psi) it bypasses the pump output to a low pressure reservoir. The pack voltage is 96 volts. I'm trying 90 VDC treadmill motors that can be obtained cheap from Princess Auto. The first one I tried was rated 0.45 HP, 5.4 amps at 90VDC. I've connected it through a pulley reduction setup with a separately mounted shaft in between the motor and pump that has a large pulley run from the motor and a small pulley running the pump. That motor drew 4-4.5 amps when its output was bypassed and 6-7 amps when pumping the pressure up. The system operates bypassed most of the time. I replaced that motor with one that looks a little stronger. I don't have specs for it but it has a thicker shaft and ball bearings rather than bronze bushings and it is rated 6000 rpm. It does seem to work better but the commutator end of the housing gets sizzling hot after 5 minutes or so, and I pulled the plug on it when smoke started to rise. It was drawing up to 8 amps for short periods, about 4-6 amps when the pump was bypassed. The initial experiments were done with just a bridge rectifier plugged into 120 V house current, but these numbers were with my 96 volt test pack (103 VDC measured). I'm not entirely happy with a setup that bleeds smoke. My question is 'what do I do now?' I'm considering: 1) bigger motor, same setup. I don't know much about motors, but I figure that any motor that will work will draw 4 or more amps from my 96 volt system, unless I make the mechanical connection less wasteful. Question for those with experience: Does it sound like mechanical efficiencies with reduce strain on the motor enough to keep the smoke in? 2) pressure switch to run the motor only when required. (problem with this is that the current regulator "cuts in" quite frequently, though only very briefly. This might be helped by a bigger high pressure reservoir). At least then I wouldn't be wasting my hard-earned amps. 3) Trash the multiple pulleys and get some gears, or try to fit a bigger pulley on the pump to increase the ratio, maybe ease up on the pulley tension to the minimum functional tension. The suspension rises lickety split with the smoking motor arrangement, so I figure that the pump could be slowed down a bit. The hydraulic output from the pump comes out the front just below the pulley, so it might not be possible to fit a bigger pulley there. 4) Get a fan for the motor and hope for the best. 5) Ask the gurus on the list... Mike Hoskinson
