Fewer hours of daylight and frigid temperatures can tempt the most seasoned crane operator or technician to take shortcuts over the winter months. But saving minutes today can result in costly repairs and significant downtime tomorrow.
Looking Up spoke with senior technical service managers Jack Kramer and Jeremy Wagaman, who support Grove, Manitowoc, and National Crane products in North America, to get a list of best practices and pro tips to keep your mobile hydraulic cranes running well through the harshest winter weather.
Ice and Snow Build-up
Keep the tops of fuel and hydraulic tanks free of snow and ice to prevent contamination of the system.
Remove excessive ice build-up on boom tip components such as sheave wheels, aircraft warning lights, and wind speed indicators.
Ensure all cable reels are free of ice and snow. Ice on wire rope, specifically for cranes with many falls of line, can cause improper rolling of sheaves in the boom tip and block, adding additional weight to the LMI system. To prevent this from occurring, slowly run the hoist to gradually break the ice from the rope. You can also gently knock the ice loose using a flat rubber mallet. Make sure the jobsite is clear of personnel before conducting these ice removal procedures.
Batteries
Avoid jump-starting or using a portable power unit to recharge batteries in the crane carrier or superstructure, as this can damage electrical systems (CCS, LMI, engine and transmission) due to voltage/amperage surges.
Manitowoc strongly recommends that batteries be completely disconnected from a crane’s electrical system(s) and charged using a battery charger of appropriate voltage level, or replaced with fully charged batteries in complete sets.
Fuel and DEF
Ensure that the fuel system is regularly drained of any water. Water can cause fuel quality problems all year round, but when the weather turns colder it can trigger additional issues with fuel lines and injectors.
If the crane has been non-operational for an extended period, drain the old fuel from the tanks and replace it with fresh fuel.
Replace the glow plugs/ignitors with new units, and check that the fuel pumps are in working order and not “gummed up” from sitting idle.
Fuel additives that help prevent fuel gelling can have adverse effects on diesel particulate filter systems, leading to derate issues. The same applies to the old-school tricks of thinning down diesel fuel with alcohol, gasoline, or home heating oil. Always refer to the engine OEM requirements regarding fuel additives.
Diesel exhaust fluid (DEF) should be stored out of the elements to avoid freezing and thawing, which can lead to premature breakdown of the product.
Proper Warm Up
Allow the crane’s engine to warm to operating temperature before running aggressively.
Check to ensure the diesel-fired air and auxiliary water heaters are working properly.
Regularly change out the filters for the fuel, hydraulic, and heating systems to assure free-flowing fluid to the appropriate devices, which can thicken due to temperatures or a change in the fluid formula used.
If your crane’s after-treatment system uses DEF, allow the engine to properly warm up for proper dosing. DEF freezes at 11° F (-11° C), so ensure the DEF tank is free of slush prior to operating. Failure to do so can lead to the engine de-rating and potentially stopping.
Once the engine and DEF are warmed, run a non-stalling function, such as the hoist, to begin moving hydraulic fluid through the system. After several cycles have been performed, run a function over a relief valve, such as tele-retract or boom-down. This pushes the cold oil across a small opening in the valve to efficiently raise the oil to a standard working temperature.
Lubrication and Greasing
Properly lubricate bearings with fresh grease to repel any water ingress and avoid premature wear.
Use the correct grease for your crane type, especially with pinned-boom systems. Refer to the operating manual to determine the correct grease to use.
Hydraulics
Take extra care when using hydraulic tank heaters. When heated hydraulic oil is suddenly pushed through cold valves, it can cause the valves to stick.
If performing duty-cycle work, where the boom is extended but static, the hydraulic oil in the boom can still cool. As noted above, run a function over a relief valve to efficiently warm the telescoping cylinders.
Cranes used in extremely cold weather (below 20° F/-6° C) can have issues with hydraulic oil. Thinner viscosity hydraulic oils can be used as long as the substitute oil is compatible with the various seals, packings, pumps, valves, etc. in the hydraulic system. If the oil is swapped for winter operations, ensure that the same oil will be suitable for warm-weather applications, or remember to replace the oil with the change in seasons.
For pinned-boom machines, it is recommended to cycle the pinning system multiple times to heat the oil. Unlock the cylinder and cycle the tele-cylinder out and back completely for several cycles to extract and replenish the thick oil in the fill tube. Next, place the cylinder in T-1 and cycle the section unlock and lock commands several times. This purges the cold oil from the opposite of the pinning head.
Weather Effects on Hydraulic Cylinders
Hydraulic oil expands when heated and contracts when cooled. Thermal contraction will allow a cylinder to retract as the hydraulic fluid trapped in the cylinder cools. To avoid a “stick-slip” condition in the boom, ensure adequate lubrication and wear pad adjustment to enable the boom sections to slide freely and smoothly.
To minimize the effects of thermal contraction or “stick-slip” conditions, it is recommended that the telescope control lever is activated periodically in the extend position to mitigate the effects of cooling oil.
If a load and the boom are allowed to remain stationary for a period of time and the ambient temperature is cooler than the trapped oil temperature, the trapped oil in the cylinders will cool. The load will lower as the telescope cylinder(s) retracts allowing the boom to come in. Also, the boom angle will decrease as the lift cylinder(s) retracts, causing an increase in radius and a decrease in load height.
This situation will also occur in reverse. If a crane is set up in the morning with cool oil and the daytime ambient temperature heats the oil, the cylinders will extend in similar proportions. Refer to the crane’s operating manual for more information on this topic.
Planned Downtime
Take advantage of planned downtime over winter months to schedule preventive maintenance inspections. It’s also a good time to stock up on wear parts. With over 470 locations worldwide, a local Manitowoc dealer is available to provide support over the entire lifetime of your crane.
As a reminder, these tips are for general informational purposes. Always consult your serial-number-specific crane operator’s manual for complete details. Additional operating manuals can be ordered through your local Manitowoc dealer.