====== Motor and drivetrain ======

The electric drive of the C5 runs:

**12 V motor** → **epicyclic gearbox** → **toothed drive belt** → **drive gear** → **rear axle**, driving the **left-hand rear wheel** only.

The overall reduction is 13:1. The pedal drive is a separate system; see [[parts:pedals:start|Pedal drive]].

===== Parts in this system =====
<nspages -title -exclude:start -simpleList -textPages="">

===== Add-ons and improvements =====
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===== How it works =====
  * The [[parts:drivetrain:motor|motor]] is a 12 V permanent-magnet DC motor rated at **250 W continuous**, made by Polymotor (Italy, part of the Philips group). It isn't a washing-machine motor, despite the legend.
  * There is **no speed control**. The power button simply switches the motor on or off through a relay, and the motor's own maximum speed (4,100 rpm) limits the C5 to about 15 mph.
  * The motor draws about **15 A on the level**, about 50 A climbing a 1-in-15 hill, and up to 140 A when stalled. It is protected by a thermistor in the armature shaft, a thermal trip on the case, and stall detection in the control box. See [[parts:electrics:start|Electrics]].
  * The motor sits in an **eccentric clamp**. Rotating it is how you set the [[parts:drivetrain:drive_belt|drive belt]] tension.

===== Golden rules =====
<WRAP important>
  * **Pedal off from rest, then use the motor.** Starting on the motor alone strains the gearbox, belt and motor.
  * **Pedal on hills.** The motor overheats on long climbs and cuts out.
  * **Don't push the C5 backwards quickly.** The motor acts as a generator and can destroy the control box's protection diode.
</WRAP>

===== Common problems =====
  * **Clicking or slipping under power:** see [[parts:drivetrain:drive_belt|Drive belt]] and [[parts:chassis:motor_support|Motor support]].
  * **Motor runs but no drive:** check the belt, and whether the [[parts:drivetrain:gearbox|gearbox]] has come off its lip.
  * **Motor cuts out on hills:** thermal protection doing its job. See [[parts:electrics:start|Electrics]].
  * **Never-serviced gearbox:** regrease it before regular use. See [[parts:drivetrain:gearbox|Gearbox]].

===== Related systems =====
[[parts:chassis:start|Chassis]] (motor support) · [[parts:electrics:start|Electrics]] (thermal trip, heat sensor, control box) · [[parts:pedals:start|Pedal drive]] · [[parts:wheels:start|Wheels and tyres]]

~~NOCACHE~~