CASE STUDY
Stop low gear engagement before it causes damage
In mobile plant, service vehicles, and specialist machinery, low gear engagement at the wrong time can do real damage.
It puts extra strain on the transmission, shocks the driveline, and creates avoidable wear on expensive components.
The challenge is finding a simple way to stop it happening without building a one-off control system from scratch.
That’s where the Bolec SS501 comes in.
Practical outcome
Stops low gear engagement when speed or RPM goes beyond the safe limit.
Why installers like it
One compact unit, two inputs, flexible output options, and simpler wiring.
Best fit for
Mobile equipment, service vehicles, specialist machinery, and custom control builds.
The problem
When a machine is travelling too fast or the engine revs are too high, allowing low gear to engage can be hard on the whole driveline.
For operators and builders, the issue is not whether a lockout is needed. The issue is doing it in a way that is reliable,
easy to wire, and practical to service later.
A lot of basic switches only look at one signal. In the real world, that is often not enough.
The Bolec solution
The SS501 Two Channel Rev Switch gives you a straightforward way to build a speed-based lockout using real operating inputs.
In this application
- Channel 1 monitors engine RPM
- Channel 2 monitors vehicle speed
- The output controls the lockout function
That means low gear can be disabled once the machine goes past a preset speed, a preset RPM, or a combination of both.
Instead of relying on one simple trigger, the SS501 lets the machine respond to what it is actually doing in the field.
Why this works so well
Two real inputs, one practical outcome
This is where the SS501 stands apart from a basic rev switch. It can take two separate frequency inputs and use them
to drive one control action.
For transmission lockout, that is a real advantage. You are not just watching revs. You are also looking at actual vehicle speed.
Built for straightforward installation
The SS501 is practical to fit and easy to work into existing equipment. It suits 12V or 24VDC systems,
has 5A internal relay contacts, and can be configured for:
- Normally open output
- Normally closed output
- Pulsing output
It also gives you adjustable high and low set points, with hysteresis to help prevent relay chatter around the switching point.
Better than a patch-up solution
Instead of stitching together multiple devices to get the logic you want, the SS501 gives you a neat, compact way to handle it in one module.
- Less wiring
- Cleaner control logic
- Easier fault-finding later
- A more professional end result
At a glance
| Item | Detail |
|---|---|
| Product | Bolec SS501 Two Channel Rev Switch |
| Main job | Prevent low gear engagement using RPM and vehicle speed inputs |
| Input setup | Dual input / single output |
| Channel 1 | Engine RPM |
| Channel 2 | Vehicle speed |
| Supply | 12V or 24VDC |
| Output options | Normally open, normally closed, or pulsing |
| Relay rating | 5A internal relay contacts |
Real-world result
- Stops unwanted low gear engagement
- Reduces shock loading on transmission and driveline components
- Simplifies the control setup
- Creates a more reliable interlock using both RPM and speed
In short, it is a smarter way to protect machinery from avoidable operator or control-related stress.
Where it fits best
| Application | Why SS501 suits it |
|---|---|
| Mobile plant | Helps prevent damaging gear engagement under changing operating conditions |
| Service vehicles | Useful where RPM and speed both need to be considered for control logic |
| Specialist machinery | Allows a more practical interlock than single-input switch solutions |
| Retrofit jobs | Compact format and flexible outputs make it easier to integrate into existing systems |
Why Bolec
Bolec gear is built with practical installation in mind.
The advantage of the SS501 is not just that it can switch on speed. It is that it gives you flexibility without making the job harder.
Where a lot of generic solutions are limited to one signal and one action, the SS501 gives technicians a more useful tool for real machine control.
That matters in the field, in the workshop, and on equipment that has to keep working.
Need a practical speed-based lockout solution?
If you are building or retrofitting machinery and need to control low gear engagement based on
RPM and vehicle speed, the Bolec SS501 is a proven, practical option.