Running reverse for forward
What Chris sees on the bench
Take a 1017-004 direct drive that was run in reverse to go forward. It melted and destroyed the gears. The planetary shaft, which is also the output shaft, connects to the input shaft through a set of gears, and it just ate all of the pieces. The drum got torn up too.
On a 1.5:1 that we'd rebuilt a few years earlier for a customer, here's what Chris found when it came back:
- The sealing surface in the case grooved, with severe metal breakup.
- Reverse plates that were pretty dirty and worn.
- A chipped tooth on the reverse planetary.
- Significant wear on the thrust washer that separates the input shaft clutch pack assembly from the reverse planetary.
- No bushings left in the reverse planetary, and signs it had overheated.
To Chris, all of that indicated the transmission was being used in reverse for forward, using the reverse clutch pack instead of the forward clutch pack.
What causes it
Here's how a cast-iron Velvet Drive works. For forward, the forward plates hold the hub and send it all through directly to the planetary and the output shaft. For reverse, the clutches spin free and the drum itself spins, turning the planetary gears, which gives you reverse. The reverse planetary gears spin about 1,000 rpm for every 100 rpm that comes in. That's why you can't run these cast-iron transmissions in reverse for forward. It smokes the planetaries.
Prevention
The shift lever has to be in the forward position to go forward. Changing pump rotation doesn't change that. Pump rotation only matches the pump to the direction your flywheel turns, and it won't change the output shaft direction. See changing pump rotation for more.
When to call
If you're not sure how your transmission is set up, call (804) 333-3677, Monday through Friday 9 to 3 Eastern, or email sales@halemarine.com.
Related reading: changing pump rotation, the five-second shifting rule and identifying your transmission ratio.