For many years modifications to grate cooler technology have continuously developed. Many of the grate coolers supplied for the cement industry over the last 50 years include hydraulic drives. Continuous developments for the clinker cooler hydraulic drive have achieved a considerable improvement of operation, reliability and capacity. The following two plant modifications are good examples of the continued development of the hydraulic drive meeting the expectations of cement plant operators. The Cemento Votorantim S.A. Fabrica Santa Helena, Brazil decided in January 2001 to make a modification to their grate cooler drive on the 2nd grate. The plant replaced the existing mechanical drive with hydraulic drive including a grate motion control, compact swing supports and a moving frame guide. The Lafarge Cementos Maua, Matozinohos plant, Brazil also decided to make an improvement on their 2nd grate cooler drive to eliminate continuous kiln shutdowns due to grate mechanical problems and improve performance. The plant replaced the existing mechanical drive with a hydraulic drive including a local control box and compact swing supports in June 2000. Comparison is made for various parameters before and after modifications for: power consumption; air volume; clinker temperature; reliability; and grate control. Special discussion for different arrangements of grates in conjunction with hydraulic cylinders complete this paper.