Manitowoc Grove RT770E, Service Maintenance Manual

Page: 206 / 357

5-6 Published 11/26/2014, Control # 447-05
HOIST AND COUNTERWEIGHT RT770E
A comprehensive hoist line pull and load holding test must
be carried out following any such repair work.
Manitowoc Crane Care offers prepackaged kits that include
all the seals, bearings, fasteners, washers, brake disks,
brake stators, sprag clutch, and springs that are required for
reassembling the hoist after inspection. During the
inspection, if components not included in the kit are found to
be worn or damaged, contact your Manitowoc Cranes
distributor or Manitowoc Crane Care to order replacement.
Usage and Inspection
Inspection procedures for hoists are divided into five general
categories based upon their usage or duty cycle, which in
turn determines appropriate intervals for inspections. The
usage categories must be assigned by the crane user on a
consistent crane-by-crane basis. The five crane/hoist usage
categories are as follows:
Idled - The crane/hoist has not been used for three months.
Infrequent Usage - The crane/hoist is used less than ten
hours per month based on a three month average
Moderate Usage - Crane/hoist used 10 - 50 hours per month
based on a three month average.
Heavy Usage - Crane/hoist used 50 - 200 hours per month.
Severe Usage - Crane/hoist is operated more than 200
hours per month OR where 50% of the lifts exceed 75% of
the rated capacity for the hoist.
The following chart lists the inspections that are required for
each type of usage category.
Preventative Maintenance
It is extremely important to be aware of the possibility that
deterioration of internal critical components within the hoist
reduction unit can occur. Hoist reduction units incorporate
planetary gears, multi-disc brake assemblies, and sprag
clutches which do not have an infinite life span. Although
these components have been designed to achieve long
service life, reliability can be substantially reduced by a
variety of influencing factors such as:
• High cycle operation.
• Operating in high ambient temperatures.
• High external contaminations, such as dusty or sandy
conditions.
• Level of maintenance.
The following should be carried out following instructions in
Lubricants and Lubrication Intervals , page 9-1 and/or
manufacturers instructions.
1. Pre-Use or Daily Inspection.
Must include but is not limited to the following inspections
that will be performed prior to placing the crane into service
and then as necessary during extended operation. This
inspection must be performed by a qualified crane operator
or qualified crane technician.
• Check for external oil leaks and repair as necessary.
This is extremely important due to the accelerated wear
that will result from insufficient lubricating oil in the hoist.
Hoists with a sight glass; check oil level daily. Hoists
without a sight glass; check oil level monthly if no
external oil leaks are detected. Lubricant level must be
maintained between the minimum and maximum levels;
midway up sight glass or at bottom of level plug port as
equipped. Use ONLY the recommended type of
lubricant. Refer to
Lubricants and Lubrication Intervals ,
page 9-1.
• Check hydraulic fittings and hoses for chaffing,
deterioration or corrosion and repair as necessary.
• Visually inspect for corroded, loose or missing bolts, pins
or other fasteners and replace or tighten as necessary.
• Visually inspect rotation indicator transmitters, anti-two-
blocking switches and other safety equipment and repair
as necessary.
WARNING
Failure to implement and adhere to a hoist inspection and
maintenance program may result in damage to the crane,
other property damage, and/or serious injury or death to
persons working on or near the crane.