how to measure main bearing clearance

{"cid":"91195998","title":"ASTM D2783 Lubricating Grease 4 Ball Method Lube Oil Analysis Equipment","imgUrl":"https:\/\/img.chinax.com\/nimg\/d2\/7e\/69ff2347c4889dc37ddc57b9ce06-200x200-1.jpg","attrs":{"Price":"Negotiable","Brand Name":"AI","Model Number":"AIC-2783","Minimum Order Quantity":"1 set Extreme Pressure Properties Tester","Delivery Time":"30 days","Certification":"ISO","Place of Origin":"China","Payment Terms":"L\/C, T\/T, Western Union","Supply Ability":"20 sets per month","Packaging Details":"Extreme Pressure Properties Test Equipment packed in plywood case","Test standard":"ASTM D2783","Test method":"4 ball method","Rotation speed":"300~1800r\/min","Temperature range":"Ambient~250\u00baC","Size":"1300\u00d7490\u00d71220(mm)","Weight":"570KG","Warranty":"1 Year","Keyward":"Extreme-Pressure Properties Test Machine,4 ball machine","Wear spots measuring range":"0~10mm","Oil volume for test":"10ml"}}