Product Overview
The RB570 transformer is the 18 VAC, 40 VA charging transformer used on select Mighty Mule, GTO, and Linear Pro battery-backed gate opener systems. The transformer does not run the gate motor directly like a hardwired AC operator; it feeds charging power through the control system so the 12-volt battery can stay charged. When the transformer fails, is damaged by weather, or is replaced with the wrong voltage, the gate may run for a while on battery and then become weak, slow, intermittent, or completely dead. On many FM500 and FM502 style systems, charging problems can also trigger audible alerts or repeated service calls.
This transformer is commonly referenced for UL-rated Mighty Mule systems and many older GTO/Linear Pro battery-charged operators. However, Mighty Mule changed power supply styles across generations, so newer MM271/MM272 and MM37x/MM57x style openers should be checked carefully because they may use RP1010 or other power supply references instead of RB570.
Compatible With
RB570 is commonly associated with the following compatible or related gate opener applications when the operator manual calls for an 18 VAC / 40 VA transformer:
- Mighty Mule FM350 and FM352
- Mighty Mule FM500 and FM502
- Mighty Mule FM600
- Select UL-rated Mighty Mule swing and slide gate openers after the March 2000 UL325 changeover
- Select GTO / Linear Pro PRO2000, PRO3000, and PRO4000 family references when the 18 VAC 40 VA transformer is specified
- Select GTO / Linear Pro SL-1000 and SL-2000 slide gate operator references when the 18 VAC 40 VA transformer is specified
- Related garage-door receiver adapter use with RB709U in some listed applications
- Excludes newer Mighty Mule MM271 and MM272 references that commonly use a different power supply
Features & Specifications
| Manufacturer | Mighty Mule / Linear / GTO |
|---|
| Product Type | Replacement transformer |
|---|
| Part Number | RB570 |
|---|
| Application | Battery charging transformer for compatible automatic gate openers |
|---|
| Voltage | 18 VAC output |
|---|
| Power Rating | 40 VA |
|---|
| Compatible Operator Type | Select UL-rated battery-backed swing and slide gate openers |
|---|
| Notes | Used for charging circuit; not a universal transformer for all Mighty Mule generations |
|---|
Also Known As / Related Part Numbers
Related part numbers and common search references include:
- RB570
- LIN-RB570
- GTO RB570
- Mighty Mule RB570
- 18 Volt 40VA Transformer
- 18 VAC 40 VA Transformer
- 18 Volt AC transformer
- MM UL transformer
- FM500 transformer
- FM502 transformer
- FM600 transformer
- Not RP1010 power supply for newer MM271/MM272/MM37x/MM57x families
Technician Note
A replacement transformer should be diagnosed with the battery and charging circuit, not by symptoms alone. A weak battery can make a good transformer look bad, and a damaged control board can prevent proper charging even when transformer output is present.
Before Ordering
- Confirm the operator manual calls for 18 VAC / 40 VA.
- Check whether the opener is an older FM/PRO series or newer MM/RP power supply generation.
- Inspect the transformer plug, wire run, and low-voltage terminals for damage.
- Test or replace a weak gate battery as needed.
- Do not install a different voltage transformer to compensate for charging problems.
Important Ordering Warnings
Using the wrong transformer can damage the charging circuit or leave the battery undercharged. Match voltage, VA rating, and operator generation before replacement.
Professional Advisory
Gate opener service can involve stored gate force, moving arms, batteries, and low-voltage control wiring. If the operator is moving unexpectedly, has damaged wiring, or has missing required safety devices, have the system inspected by a qualified gate technician before returning it to service.
Product-Specific Q&A
What does the RB570 transformer do?
It supplies 18 VAC charging power through the gate opener control system so the operator battery stays charged.
Is RB570 used on every Mighty Mule opener?
No. It is used on select UL-rated Mighty Mule, GTO, and Linear Pro systems. Newer Mighty Mule MM271/MM272 and MM37x/MM57x generations commonly use other power supply references.
Can a bad transformer make the gate slow or dead?
Yes. If the battery is not being charged, the gate may become slow, weak, intermittent, or stop working once the battery is depleted.
Is this a motor power supply?
No. On these battery-backed operators, the battery powers the gate motor and the transformer maintains the battery charge through the control system.
Should I replace the battery at the same time?
If the battery is old, swollen, weak, or fails a load test, it should be replaced or tested before blaming the transformer alone.
