dynamo?

Bill8200

New member

Equipment
B8200
Oct 12, 2020
24
1
3
PA
why does my tractor have a dynamo instead of an alternator? what's the difference and why do you think the engineers made that choice?
 

GreensvilleJay

Well-known member

Equipment
BX23-S
Apr 2, 2019
1,487
129
63
Greensville,Ontario,Canada
cheaper and simpler to make..less parts = more profit !
A 'dynamo'( to me anyway) has spinning magnets so no brushes ( same as riding lawn mowers). Overall, they're more reliable..nothing to wear out and very simple(cheap) to change power to charge batteries, etc.
 
  • Like
Reactions: 1 user

In Utopia

Member

Equipment
L175 FEL
Apr 21, 2013
435
7
18
Utopia,Tx/Pasadena,TX
A dynamo produces direct current while an alternator produces alternating current. A dynamo has a commutator while an alternator doesn't. A dynamo is less reliable than an alternator. A dynamo based system is less efficient than an alternator based system.
 
  • Like
Reactions: 1 user

85Hokie

Well-known member
Lifetime Member

Equipment
BX-25D w/ Filled Rears,2" Spacers,PTB. Under Armor, 90'-90'-92'-B7100HST's
Jul 13, 2013
7,496
125
63
Bedford - VA
why does my tractor have a dynamo instead of an alternator? what's the difference and why do you think the engineers made that choice?

In the true sense of the word - dynamo ..... that is a DC voltage producing device, a true dynamo has a commutator that produces DC.....

What you have is a really an Alternator - though many call it a dynamo - there is no commutator inside the device - a magnet is spun around a large set of windings to produce an AC voltage. And your voltage reg handles the rest - controlling the output and converting it to DC.

as Jay say - cheap and easy to produce. These devices are almost bullet proof - the only thing that goes bad in these devices are the set of bearings ..... BTDT!

Here is the inside of a "dynamo" that the bearings decided to exit stage left!
Notice the filings and bearings and how they are "stuck" to the magnet.

EDIT - In Utopia beat me to it!!!


2016-03-31 14.54.23.jpg
 
Last edited:
  • Like
  • Wow
Reactions: 2 users

GreensvilleJay

Well-known member

Equipment
BX23-S
Apr 2, 2019
1,487
129
63
Greensville,Ontario,Canada
yuck ! I had a B&S that wouldn't turn over.... tore it apart, fearing a broken rod...nope, several of the magnets inside the flywheel had broken off !! well at least one, it took out the next one, then that took out the next one......
Easy fix, replaced flywheel.
 
  • Like
Reactions: 1 user

ken erickson

Active member

Equipment
B7100 hst, 2650 front mount snowblower, L2501 hst qa loader
Nov 21, 2010
130
31
28
Waupaca Wisconsin
And can be a challenge to remove on a B7100 HST, especially that one #$%@ nut and washer.
IMG_1579.jpeg
IMG_1565.jpeg
 
  • Like
Reactions: 1 user

N3BP

Member

Equipment
B7200DT, L2900GST
Sep 20, 2016
91
5
8
Lebanon, PA
You can upgrade to a standard alternator, pending you find (or fab) the necessary bracketry. Here is a pic of my setup:
 

Attachments

  • Like
Reactions: 1 users

Bill8200

New member

Equipment
B8200
Oct 12, 2020
24
1
3
PA
Sooo, is a generator just another name for dynamo or is it something completely different?
 

GreensvilleJay

Well-known member

Equipment
BX23-S
Apr 2, 2019
1,487
129
63
Greensville,Ontario,Canada
Kind of a 'war of words', depending on what part of the world you live in...
to me, in Canada,eh...

dynamo, is a device with a rotating magnet and a fixed coil that produces power
generator, a device with a powered field coil, brushed making DC power
alternator, a device with a powered field coil,brushes making AC power

in the 'grand scheme of things' ,dynamos are simple cheap and fewest problems. Aside from bearings( common to all) , not much can fail. electrically only one component the 'coil'.
 
  • Like
Reactions: 1 user

hope to float

Member
Lifetime Member

Equipment
L3450
Feb 18, 2018
375
17
18
Ireland
Kind of a 'war of words', depending on what part of the world you live in...
to me, in Canada,eh...

dynamo, is a device with a rotating magnet and a fixed coil that produces power
generator, a device with a powered field coil, brushed making DC power
alternator, a device with a powered field coil,brushes making AC power

in the 'grand scheme of things' ,dynamos are simple cheap and fewest problems. Aside from bearings( common to all) , not much can fail. electrically only one component the 'coil'.
Had a dynamo on the old MF135 and, while the dynamo itself only failed once, the voltage regulator and solenoid used to pack in every 2 years or so.
 
  • Like
Reactions: 1 user

lugbolt

Well-known member

Equipment
ZG127S-54
Oct 15, 2015
2,399
83
48
Mid, South, USA
kubota calls it a dynamo. Y'all remember when I referred to Kubota's terminology as "Jinglish"? Thats one of many examples....it's not really a dynamo, it's technically an alternator but whatever.

They rarely fail when they do it's usually bearings. The majority of the time the bearings seize and the magnet/pulley assembly just stops turning and burns the belt up. Sometimes the owner recognizes the stench and sometimes they keep going and burn the belt OFF, then it overheats and destroys the engine in some cases. Most of the time it just seizes or loses power and then they shut it down. By then the engine has been so hot that the head is cracked and gasket blown. Very common.

those dynamo's typically run for thousands of hours with no problems. A lot of times I'll get customers that bring aged equipment in for FULL servicing (including valves) and I'll pull the fan belt off and spin the dynamo, if there is ANY bearing noise, replace the bearings or the dynamo whichever is cheaper. Usually bearings. As long as they ain't seized/destroyed the bearings come out pretty easy but once they are gone the outer race is all that is left and it can be a bear to get out of the housing it's resting in.

I too hated the B7100's......glad I don't work on them anymore!!
 
  • Like
Reactions: 1 user

torch

Well-known member

Equipment
B7100HSD, B2789, B2550, B4672, RC54-71B, 48" cultivator, homemade FEL and Cab
Jun 10, 2016
1,486
64
48
Muskoka, Ont.
The original definition of 'dynamo' did not specify AC or DC. It simply meant a means of converting mechanical energy to electrical energy. Same with 'generator'. 'Dynamo' has come to mean a DC generator in general use, but the Japanese were not wrong in applying the term to the brushless alternator.

Similarly, in the automotive world, 'generator' has come to refer to a DC device. However walk into a Home Depot and ask for a generator and you will be directed to a wall of AC producing equipment. (Some of which may actually produce high-frequency AC, then convert that to DC, then invert that into 60hz AC at the outlet. )

'Alternator' is the only term that definitively specifies AC vs DC.
 

In Utopia

Member

Equipment
L175 FEL
Apr 21, 2013
435
7
18
Utopia,Tx/Pasadena,TX
When the alt. in my L175 died I replaced it with what some people call a hotrod alt.
They are small, come with a pulley and are one wire.
Mine puts out 14.7 volts at idle.
Something like this is what I'm talking about.
 

Henro

Active member

Equipment
B2910, BX2200
May 24, 2019
518
54
28
North of Pittsburgh PA
even more cornfusing, is that 'car alternators' actually have the diodes ( used to convert AC into DC) built INSIDE,so as a 'black box'.. it converts rotary motion into 3 phase DC......
3 phase DC? LOL :love:

While it does not really make any difference in practical terms, the diodes do rectify the AC to DC, which has a ripple on it that relates back to the frequency being rectified. This frequency will vary according to engine RPM. But the output is DC none the less.