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Coach won't start/semantics

Yahoo Message Number: 70662
Not that it has any practical application to the problem at hand (nit picking) but I notice we are all to some extent using the terms "solenoid" and "relay" interchangeably so I checked the dictionary and see that a solenoid is a coil that produces a magnetic field when current is passed through and a relay "2 an electrical device, typically incorporating an electromagnet, that is activated by a current or signal in one circuit to open or close another circuit".

In our coaches the relays are usually devices that incorporate a solenoid - not necessarily interchangeable terms or mutually exclusive.

I'm not sure how one would characterize, for example, a mechanical plunger latch driven by a solenoid to remotely secure or release a storage bay door. It isn't a relay but does incorporate a solenoid and could get its current through a relay. I'd call it a solenoid but not a relay. I had an old bus that had a solenoid driven rod that that physically moved the start drive ring gear (?) to engage the engine flywheel when starting while power was simultaneously supplied to the starter motor through a relay powered by a small low current wire switching a high current capacity wire running as short a distance possible between the start battery and the starter. Generally, I think in terms of a starter solenoid as being physically attached to the starter and the starter relay (also containing a solenoid) somewhat more remote being powered by a low current probably from the distant start switch to allow large starting loads direct from the battery to the starter.

Jim M

'02 Intrigue #11410 ISL 400

Coach won't start/semantics

Reply #1 –
Yahoo Message Number: 70666
A relay mostly has a fixed pole piece that when energized magnetically pulls in a movable set of contacts to switch current on or off.
A solenoid has a movable armature that moves in or out when energized or de energized.
This armature can be connected to a set of heavy duty contacts or some other mechanical device like a starter Bendix drive.

Charlie

Re: Coach won't start/semantics

Reply #2 –
Yahoo Message Number: 70669
Ah,

But a Bendix drive is not solenoid activated, it is activated by a rotating shaft operating against the at rest momentum of the pinion gear, thus driving the pinion gear into the flywheel gear against the Bendix drive spring, via a helical spline cut into, or connected to the starter motor shaft, and later, the friction of the engine components after the pinion gear engages into the flywheel gear. And later disengages due to the increased rotational velocity of the pinion gear with respect to the starter shaft rotational velocity at the point at which the motor engages (or the starter stops turning), and drives the flywheel and in turn the pinion gear at a high rate of speed, thus reversing the travel of pinion gear up the starter motor shaft and against the Bendix drive spring.

Mike 03 Lexa