Hi team, am trying to adjust the tray on a caterpillar 789b that comes down hard on the frame with a bang. Have read the manual but there is nothing. Please help.
Are you getting a correct indication for body up/down from the magnet and the proximity switch located on the LH frame rail.? When the Body Up status changes from UP to down as the body approaches the framre the hoist control should go into snub to slow down the speed of the hoist cylinders.
Good afternoon Nige, I thought that was only for the C series. Since the control valve is fully mechanically operated, how does the switch control the flow of oil to control the hoist cylinder??
Sorry about that. I was mixing up data from C-Series with B-Series. The electronically-controlled hoist valve came in with the C-Series I looked at it a bit deeper and the chassis rail proximity switch is an input into the EPTC-II which, when it's in the UP position, inhibits the selection of reverse gear and limits forward gears to first speed. Do you have access to the SysOp or Testing/Adjusting documents for the Hoist system.? I can post them up if you need them. Also I'm wondering if the diverter valve that sends brake cooling oil to the hoist circuit might be on the fritz and allowing too much flow through hte hoist valve in the FLOAT position.?
The diverter valve was changed out with a new one but no change. Can you send me the documents as mentioned please.
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Not sure about a 789 but our 773’s have a restriction plate on the return line on the bed cylinders. If someone removed those when changing a busted line that could be the problem.
There is a signal line to the counterbalance valve from the block on the centre of the torque tube that contains an orificed plug ref #31 right next to the elbow coming out of the block. It's shown as Ref #66 on the Hydraulic Schematic. Has the orifice become blocked or maybe even the orifice plug been left out completely.? Also check out items ref #65 & 68 on the hydraulic schematic, especially #68 which is a vent from the rod end of the hoist cylinders.