I think this refers to a soil pulverizer.

http://bit.ly/1jsbovq : “Tractor Soil Pulverizers mount to the three point hitch of your tractor and are used to scarify, breakup, smooth, and prepare dirt areas such as arenas for use, or to prepare rough dirt areas for primary seeding (seed bed) prep.”

http://www.tractorbynet.com/forums/attachments/12762-using-p...

http://zhidao.baidu.com/question/261189665.html: 好；带强压的拖拉机犁地好一些不带强压的车犁不下去的田带强压的就可以犁下去；再简单点就是和过去的老推土机一样；把车的重量压在犁上；犁想不进土都不行；不过带强压的车配农具时要配结实些的农具

http://tieba.baidu.com/p/1067560295: 强压就悬挂装作可以向上提升农具也可以使农机具向下用力。硬地快有用，多不了多少钱，可以买。

http://sxyulin.ganji.com/tuolaji/304411484x.htm
http://yancheng.baixing.com/tuolaji/a276222419.html
http://www.everythingattachments.com/Tractor-Pulverizers-Yar...