Archive for the ‘Security’ Category

Procuring a Replacement Rear Door

Tuesday, July 14th, 2009

In thinking about the usability, security, and safety of the bus, I’ve come to the conclusion that the rear “ramp” installed by a former owner needs to be undone.

Converted schoolbus, rear door

It currently latches from the outside, so it’s not usable as an emergency exit without moving the hasps to the inside. It’s very heavy and the handle is high up, so not everyone I know is capable of lowering it. With the hasps inside, in a fire one could unlatch it and push it open to let it fall to the ground; but in other use, it would require two people (inside and out) or a winch to open carefully. It just doesn’t work for me.

First Junkyard Trip

Last Monday on my way home from a holiday trip to Lawrence, I stopped at the junkyard between Newton and Walton to look around. I hadn’t planned the visit and had neither target dimensions nor a tape measure with me; but I quickly found a bus that suggested a return trip was worthwhile.

Rear end of Bluebird bus in junkyard


Automotive Window Motor for Power Bus Door?

Saturday, June 20th, 2009

Converted schoolbus, rear door

Currently if the bus is closed, I have to open the heavy rear door to get in.

Converted schoolbus, right front interior

I don’t have a good picture of just the door, but the rod going horizontally across from the handle in the center of the bus to the door (hidden behind the cabinet) mechanically holds the door closed (by design) when the handle is latched in the closed position. As long as the handle stays latched, you can’t open the main passenger door from the outside.

With my highly-skilled momentum technique, I can close the front door from the outside so I don’t have to walk around, open the rear door, walk through, close the front door, walk around, and reclose the rear door; but once done, I then have to do the hokey-pokey to get back in.

I’d really like to be able to lock the passenger door and have a way to get in from the outside. And unlike many other bus-RV converters, I really don’t want to replace the bus door with an RV door — I’m not out to hide the fact that the vehicle started life as a bus. Until I have good reason to feel otherwise, I’d like to keep the accordion-fold door.

I’d love to motorize the door and add electronic entry — although at least in the long term, I need to have a purely mechanical way to get in, as backup in case something goes wrong with the motor.

Automotive Power Window Motor

Automotive power window motor assembly

“Neighbor Dan” has a pile of removed auto parts in the corner of his shop, and a guy comes by occasionally to haul the pile to a scrapyard. Dan has offered me anything I want out of the pile, and he says he has three more of these power window motors that I haven’t found yet. I’ll keep digging.

I don’t know that this is the motor to use for my power door, but it bears consideration.

Automotive power window motor assembly, opened

It looks pretty obvious why it was replaced — the cable is all messed up and broken where it wraps around the spool.

Automotive power window motor

With the jammed-up cable spool taken care of, the output shaft spins at almost two rotations per second. That’s a little fast if I were going to attach it directly to the door-opening handle or use it to replace the handle altogether. If I were to do that, I might use pulse-width modulation (PWM) to slow it down.

The motor coil resistance is 1Ω or less, so the motor draws at least an amp and I’d need a pretty hefty FET to drive it. (A compensating factor is that the motor would normally have a pretty short duty cycle, so the FET wouldn’t have long to heat up.)

Alternatively, I could use the motor with the spool and cable (maybe one of the others isn’t as messed up) and use a larger pulley / spool on the handle end to “gear down” the rotational speed.

I’ve considered that I could remove the manual handle, do away with the connecting rod, and fabricate an entirely new means to close the door. But as it’s constructed now, the rod does double-duty closing the door and “locking” it shut once closed. If I did away with it, I’d have to recreate that functionality on my own.

I’m Open to Something Completely Different

If someone knows of a better way to lock and unlock a bus front door from the outside, or motorize an accordion-fold door, I’m all ears.

Making a Key for the Locking Gas Cap

Friday, June 12th, 2009

Locking gas cap with homemade key

The bus has a locking gas cap but didn’t come with the key. Fortunately the cap was unlocked, so I could at least fill gas. Also fortunately, I found in the glovebox the original gas cap. So last night I put the original cap onto the gas tank and brought home the locking cap to make a key.

While taking off the gas cap and fishing out the retaining wire, I noted that this fill spout has nothing for the lock to lock against; so there’s no way I can see for this cap to actually lock. So why did someone replace the original with a locking cap? Because of the retaining chain — the original cap didn’t have one, there’s no good place to set the cap while filling, and the retaining chain is very handy to keep the cap captive.

That left me with a removed locking gas cap and no reason to make a key for it. But I already had the cap loose; so why not go ahead with an evening’s keymaking entertainment.