Monday, June 20, 2011
Ergonomics
It can’t be just me who gets annoyed when stuff isn’t quite where you’d expect it. It doesn’t matter if it’s the supermarket that has shuffled the aisles or a new piece of equipment that doesn’t work in the same way as the old. Some of these really stick in your mind. Twenty years ago I drove a Austin Montego, remember those? It had electric mirrors, that was pretty spectacular back then. The trouble was you had to lean forward to reach the adjustment switch…. I’ll leave you to think that through. Another car that sticks in my mind was a Honda Legend. It had electric seats with preset buttons . The problem here, was my wife always had the seat right forward so every time I drove the car I had to stand in the rain until the seat had wurred back far enough for me to jump in. A manual seat can be banged right back in fractions of a second and adjusted in the dry.
When you’re writing a PDS you can make sure the design complies with the 95 percentile man etc but it the application that always catches you out. Back in my early Girling days I remember my boss panicking because another actuator had snapped off a Twinstop brake fitted to a Ford Transcontinental. It had sailed through it vibration test without an issue. After much heartache he discovered drivers were using it as a step to get into the cab because the steps weren’t convenient!
When you’ve finished the design there’s always a modification or cost down waiting to mess up your work.
A few years ago when my Peugeot 106 was designed the conversion to RHD involved fitting a couple of bell-cranks and a tension tube to operate the brake servo. This seems to work fine. I notice the Citroen C3 uses a torsion bar under the instrument panel. I guess this is probably cheaper but the tube is twice the diameter. Unfortunately on the Picasso version the passenger can push the operating arm with his foot and apply the brakes with a similar level of effort. Citroen are now recalling 20,000 cars to fix the problem.
I doubt very much if the PDS said “ensure the passenger cannot apply or prevent the brakes from actuation” but it will in future won’t it!
Has anybody done a crash test on a RHD car fitted with such a beam???