Call A Spade A Spade
I suspect you are talking about the harrow.
Hydraulics are simpler but when the rod seal leaks you leave a trail of fluid down the pile and some plant operators might accuse you of contaminating the product regardless of the downstream calcining operations.
A rack will wear out faster than a rod seal and so I'd risk the hydraulic setup.
Don't forget to make sure that the harrow drive shuts down properly sequenced after the chain drive or else you will harrow material down and make the next start up more stressful. 
I've had a harrow run on and bury the scraper buckets even though the drive ahd long since stopped because the guide roller tracks had worn through and come adrift. 
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Rake Drive for Scraper Reclaimer
Dear Friends,
We have two 50,000 ton limestone pile with the width of 36 m. the pile staked chevron method. Our reclaiming equipment is a scraper bridge reclimer, which kind of the following rake do you recommended?
1. A rack with a hydraulic drive and 2 m stroke
2. A rack with motor reducer drive and 10 m stroke
Please mention the advantage and disadvantage of each method for cement industry. ■