25 hp jinma tractor starter drags

[Soundguy]

The key switch.. which powers the coil for the solenoid may well be fused.. however the big wire from the bat will surely hit one side of the solenoid, and another large conductor from there to the starter.. I'd be highly surprised to see a fuse in the starter primary line.. it would have to be in the neighborhood of 150-400a !!

soundguy

 

[Amez]

I believe the starter solenoid takes a lot less than 400A.

 

[Soundguy]

The coil on the solenoid only draws a few amps.. the starter however, depending on model, will dray many amps.. IE.. 150+ , again.. depending on model.

I have yet to see a tractor with a fuseinline with the starter. Got a pic of one? and an electrical schematic?

Remember.. I'm refering back to your post #27 where yo asked if running the starter and glow plugs at the same time would blow the 30a system fuse.

Since the starteritself is not on the same circuit as the 30a system fuse, then it is imaterial to the discussion of whether it will cause the glow plugs to blow the fuse.

Kinda like asking if your tail lamps will blow the gigarette lighter fuse. 2 different circuits.. thus no tangible impact on each other. The coil for the solenoid would be on the same circuit as the 30a system fuse and the glow plugs.. but as I mentioned.. the coil for the solenoid will be a realitively low current device.. compaired with the starter which is a high current device on a seperate circuit. IE. the solenoid is an electrical device that incorporates two seperate circuits.. a low current circuit is energized in order to pull inthe contacts which will make connection on a high current circuit.

If the few amps of the solenoid coil make the 30a system fuse pop when used in conjunction with the glow plugs.. then IMHO.. the circuit is not designed with sufficient tolerance..

Note.. I'm not saying the solenoid coil takes high amperage... I'm saying the starter takes high amperage. I'm also making the distinction between the 2 seperate circuits used in a solenoid.. a fused low amperage circuit.. and an unfused high amperage circuit.

as far as starter draw on a large diesel tractor starter.. you may be surprised if you think 400a is out of the ballpark!

soundguy

 

[Amez]

Sorry , maybe I should have been clearer. I understood starter energized = solenoid circuit energized (normally)

Remember.. I'm refering back to your post #27 where yo asked if running the starter and glow plugs at the same time would blow the 30a system fuse.

soundguy[/QUOTE]

 

[greg_g]

I'm sensing some mutual interference here. On a JM284, the starter MOTOR circuit is not fused. Neither the starter SOLENOID nor the glow plugs are directly fused. That's not to say however, that they are completely without electrical protection. Each passes through the keyswitch on separate and unfused circuits. But the keyswitch itself is protected by the 30A system fuse. By extension, so are the solenoid and glow plugs.

That said, I've read that some later model Jinmas now have a fuse dedicated to the glow plug circuit. What I can't say though, is whether or not that mod is applicable to your JM284.

Amez - while he's been around tractors of this vintage design for many years, Soundguy doesn't own a Chinese tractor. So bear with him when he posts generic statements. His comments are usually applicable, just not always specific to the model being discussed.

//greg//

 

[Soundguy]

However generic.. in this case.. actually fairly correct.

starter power unfused.

solenoid and glow plugs fused by the system fuse.. unless I missed something.. right?

Soundguy

 

[billbill1]

The power wire goes through the Amp gauge as well, on mine, the connection on the back of the amp meter became loose, causing my starter to get less than full voltage to the solenoid, thus the starter seemed to drag. New amp meter and no more problems, might be something you want to check.

 

[Soundguy]

The power wire goes through the Amp gauge as well, on mine, the connection on the back of the amp meter became loose, causing my starter to get less than full voltage to the solenoid, thus the starter seemed to drag. New amp meter and no more problems, might be something you want to check.

Most charge systems that are 'net' charge/discharge have ALL the loads ( except the starter itself ) on one side of the amp gauge, plus the charge line from the alternator , genny, dynamo.. etc... then the other side of the amp gauge goes solely to the battery ( or hot solenoid leg ).

Soundguy

 

[greg_g]

This one's a little different Chris: Here's a vintage Jinma 200 series wiring diagram. It does not show the fused glow plug circuit reportely found in more recent Jinmas.

In this one, the preheat circuit goes from the keyswitch via wire #12 to buss bar #13 to the glow plugs (27). They use the cylinder head for ground return. The starter circuit goes from the keyswitch via clutch pedal interlock (28) straight to the solenoid. As should be now clear, neither is fused. But the keyswitch is.

Note that charging voltage from the alternator (5) travels via wire #4 to the supply side ammeter post (12) on the way to the keyswitch (13). When in the ON position, the keyswitch then sends charging voltage back to ammeter. The load side of the ammeter is then connected to the 30A system fuse in the fuse panel (7). From there fused charging voltage is back sent back to the starter solenoid battery post (6). That's the circuitous path that charging voltage takes to finally arrive via cable at the battery (1).

Lot of small gauge wire resistance in that path. It's for that reason that I have added a length of insulated 10 gauge primary wire, directly connecting the alternator output and the starter end of the battery cable. Up side is good charging voltage at the battery. But since electricity takes the path of least resistance (10ga) major ammeter deflections are dampened significantly. I think a more sensitive meter movement would fix that little problem. But I think improved starting voltage is more than a fair trade-off for a less accurate ammeter.//greg//

 

[Soundguy]

Herein lies the logical falacy:

As should be now clear, neither is fused. But the keyswitch is.

They are both fed of fthe key switch which is fused.. thus BOTH are fused circuits.... to test this.. remove the fuse fro the key switch and neither circuit will work if they are fed of fthe key switch.. thus the system fuse is a material series component to the parallel circuits fed of of it.


If the key switch is fused, and other circuits are fed of fthe key switch.. then ALL circuits are fused.

IE.. if you have a series circuit wtih parallel legs, and the series circuit is fused.. ALL parallel circuits are protected by the common fuse (feeding the key switch, in this case.)


Here is an exact analogy:

Look at your house wireing.. You have 1 breaker ( or fuse ) for each room ( or zone ) in many cases.. both receps and hard wired lamps. The receps and lamps are protected by the fuse/breaker. If you walk in a room and plug in a hair dryer... the hair dryer is ALSO protected by the same breaker that protects the recep it is plugged into. Just because there is no fuse inthe line to the hair dryer does not mean, that in an electrical sense, that it is unprotected.

When yuo chart out a complex parallel circuit with series components, you can actually make a bunch of simple series circuits out of each parallel circuit in order to make it easier to understand.. In this case.. the fuse would be par of the series circuit, and thus COMMON to all of the parallel circuits.

Thus.. if the key switch is fused.. anything comeing from the key switch is also fused... that's 9th grade intro electronics 101 basic AC and DC circuits. I have managed to keep every electronics book I used in school/college for each course I took... and this stuff I discussed right here is chapter 3.. chapter 1 being ohms law theory, and chapter 2 being components. chapter 3 being basic ac/dc circuit starting with simple circuit design.

If you can put your pencil on the schematic and travel from the + battery terminal, thru a fuse, then thru a load, then to ground.. that circuit is protected... don't matter about intervening switches.

An exception exists for relay driven loads.... if the starter key switch, drives a relay for the glow plugs, and the source for the relay power contact is not fused, then only the load ( relay coil ) is fused... and the glow plugs, like the starter, are unfused.

Really simple stuff..

Soundguy