Gravely HD ZT 60 Parking brake question

[bullet bob]

When I engage the parking brake on the mower, it only locks down the right side. Many time I've gotten up, with the engine running, only to look back and find the mower slowly turning in a circle to the right. Have to be real careful finding 'neutral' with that left control bar. Is this normal or does the brake only engage the right side? Thanks all.

 

[bertsmobile1]

Each wheel has it's own brake and a neutral adjustment.

 

[bullet bob]

Each wheel has it's own brake and a neutral adjustment.

So should the parking brake set each wheel? Or just the one?