World

Study Proves the Importance of Correct Selection of Excavator Cylinder Seals

Published

6 years ago

May 16, 2019

The working condition of the excavator cylinder is very hard. Challenges are as follows: the working pressure of the hydraulic system is large; the impact pressure is relatively high; the lateral load is large; the working temperature and the moving frequency are relatively high. Therefore, the performance of the excavator cylinder will have a direct impact on the quality of the entire machine.

Excavator cylinder components mainly include: a cylinder, piston, piston rod, bumper, external seals and standard parts.

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1. Piston seals

The seal of the piston is composed of a wear ring, an anti-pollution seal ring and a combined seal ring.

The wear ring can support and guide the piston to avoid eccentricity or scratching, and it has a certain effect on enhancing the durability of the seal. The support belt must be a product with high load carrying capacity.

Wear ring for the general use of cloth to strengthen the interlayer phenolic resin. It has good wear resistance and bearing pressure. The pressure of the phenolic cloth guide belt can reach 300Mpa, which is ten times that of the Teflon bronze guide belt. The anti-pollution sealing ring can effectively avoid the oil mixing in the cylinder. Impurities cause damage to the seal. And to provide a guarantee for the life of the seal.

The material of the anti-pollution sealing ring is a polytetrafluoroethylene resin with good immersion impurities. It has a slit and a hydraulic bypass groove in the structure, which can effectively avoid the accumulation of oil pressure.

Two-way combination seals are often used in cylinder piston seals because they save space.

2. Sealing of the piston rod

The sealing structure of the piston rod includes: a sealing ring, a buffer ring, a retaining ring and a dust seal.

The seal ring has the function of sealing hydraulic oil. There is a high demand for the choice of sealing ring material, which not only has good impact resistance, wear resistance and crush resistance but also has superior sealing properties. The buffer ring acts as a buffer for decompression of the high pressure oil in the high pressure oil, thereby further reducing the pressure of the main seal. There is a retaining ring at the bottom end of the seal, which has strong anti-squeezing ability, so it can effectively prevent the buffer ring from being squeezed. In addition, the pressure generated by the retaining ring and the main seal can lubricate between the piston rod and the guide sleeve. Friction, but this requires that the buffer ring must have a reflow property to prevent excessive pressure between the buffer ring and the main seal. Therefore, the material of the buffer ring must have good wear resistance and crush resistance. Impact resistance.

The dust ring not only effectively isolates the dust, it also protects the equipment, and it also protects against oil. The movement of the live rod in the guide sleeve requires a certain oil film to be lubricated. The outer lip of the dust ring is likely to cause the oil film to aggregate to form an external leak. Therefore, this requires the inner lip of the dust seal to have a certain anti-scratch effect, hinder the leakage of the oil film.

3. Static seals

Excavators are sealed with O-rings, using nitrile rubber as raw material, and Shore hardness is in the range of 75-90. Because of the high system pressure, the 0-ring needs to be added with a retaining ring to avoid the occurrence of the O-ring being squeezed into the fit gap.

Standard of the sealing performance:

(1) Clearance of the seal ring

In the piston seal and piston rod seal, there is a certain gap between the movements. Factors affecting the gap size include: system pressure, seal material and section thickness, dynamic edge diameter and environmental degree. If the gap is large, not only will the tearing of the sliding edge of the seal root and the stationary side cause the root to be squeezed out, causing the seal to fail. Therefore, the size of the gap has a direct impact on the sealing performance, service life and processing cost of the seal.

(2) Guide belt width

Depending on the use of the guide belt to allow deformation, the corresponding curve can be selected, and the smaller telescopic deformation can ensure the guiding effect. The minimum guide strip width can be determined from the corresponding values and formulas, and then the appropriate guide strip width can be selected.

(3) Assembly and inspection of oil cylinders

When assembling the cylinder, firstly, the parts of each part are separately loaded into the relevant components, and then installed from the inside to the outside.

It is important to choose the correct excavator cylinder seal. YBAS offers professional and high quality seal kits.

World

Criminal probe focussed on Mehtas shipping business

Published

3 weeks ago

August 6, 2025

Jonathan Grilli

From Monitoring Desk

DUBAI: An Asian family linked with the shipping business is facing criminal investigation in several jurisdictions including in Dubai and Far East where the family’s companies are under active investigation now, according to the authorities in three countries.

Sanjay and Gaurav Mehta, through their companies Best Oasis Ltd in Dubai and Priya Blue Industries in Gujarat, are facing investigations over money-laundering suspicions and suspected links to the Russian oil sector, sanctioned by the western countries, sources shared.

Sanjay and Gaurav Mehta, through their companies Best Oasis Ltd in Dubai and Priya Blue Industries in Gujarat have projected an image of environmental responsibility in ship recycling. They have tout certifications, attend global summits, and positioned themselves as ESG-compliant but their business practices have come under intense probe now. Their operations reportedly involve dismantling high-risk ships, using cash transactions, and leveraging political connections to avoid accountability, a source shared looking into the companies’ affairs. The investigation is being conducted in Dubai and the Far East.

The investigators are looking at the Mehtas operations dating back to 2006 when they came to attention of the law enforcement for the first time. Priya Blue dismantled the “Blue Lady” in 2006, a vessel containing over 1,200 tons of asbestos and radioactive waste, despite protests and objections from Greenpeace. Later, the “Exxon Valdez,” notorious for a major oil spill, was renamed “Oriental Nicety” and dismantled by the Mehtas in Gujarat, drawing international attention. In recent years, their transactions have become less conspicuous but reportedly more hazardous.

In 2025, Best Oasis allegedly acquired and dismantled at least four vessels linked to sanctioned entities, including Iranian and Houthi-controlled networks. These weren’t obscure ships; they were designated under U.S. terrorism sanctions for their involvement in oil smuggling and arms transport. According to investigators, here are the details of the sanctioned ships dismantled by Best Oasis in 2025: IMO: 9155808, Name: NOLAN (SOLAN), Sanction: SDN (SDGT), Beaching: 31 Jan 2025, Plot 16; IMO: 9221657, Name: BLUEFINS, Sanction: SDN (SDGT); Beaching: 26 Feb 2025, Plot 16; IMO: 9105085, Name: CONTRACT II, Sanction: SDN risk, Beaching: Arrived mid-2025, Plot 27; IMO: 9209300, Name: GAMA II, Sanction: SDN (SDGT); and Beaching: Pending/Planned, Plot 34

All four vessels were reportedly dismantled in Alang on plots leased by proxy firms connected to the Mehtas. These short-term leases, approved on a ship-by-ship basis by the Gujarat Maritime Board, reportedly make regulatory oversight nearly impossible. Once dismantling is complete, plot registrations often lapse, leaving no long-term record, according to documents shared by the investigators in Dubai.

Rahul Mistry, a shipping compliance researcher, noted this as a growing pattern: “This is a pattern we’ve seen more frequently in the last two years sanctioned hulls arriving under the radar, processed fast, with no digital trace.”

Payments for these vessels reportedly bypassed normal financial channels. According to sources familiar with the deals, transactions were settled in cash, either on-site or through offshore handlers. One source described entire ship values being paid in foreign currency bundles, avoiding Indian and Dubai banking disclosures, said one of the investigators familiar with the matter.

A retired port official Mr. Akin Yadav, familiar with Alang and Gujarat Maritime Board approvals stated that short-term leases are routinely used to avoid scrutiny, adding, “It was never meant to be a permanent workaround. But it’s become one.”

Political connections also reportedly play a role. Union Minister Mansukh Mandaviya and Gujarat State Minister Jitu Vaghani have been linked to approvals granted for Best Oasis and its proxies. While there’s no direct evidence of personal gain, sources allege that both men used their influence to expedite approvals, slow down inquiries, and shield the companies from enforcement.

Despite these activities in India, Best Oasis is expanding under new branding. A recent joint venture in Japan with Hiroshi Abe is being marketed as a clean, regionally responsible recycling partner for Japanese shipowners.

Mariko Fujita, a Tokyo-based maritime consultant, observed, “They’re presenting themselves as a new entity with no reference to past controversies. But none of the underlying ownership or structure has changed.”

In Alang, the situation reportedly remains much the same. Plot numbers are reassigned, cash continues to circulate and the same network of breakers and handlers is reportedly involved. Individuals like Jayant Vanani (also known as Budhabhai Patel) and Ramesh Mendapara are frequently named in connection with specific beachings, including “Contract II” and “GAMA II.” Both have been previously linked to other shadow transactions involving distressed or sanctioned tonnage.

Several yards allegedly connected to Best Oasis, including Shantamani Ship Breakers and Sai Baba Ship Breakers, reportedly operate with minimal inspection, despite numerous reports of irregularities in worker safety, hazardous waste disposal, and compliance with Indian scrapping codes.

This system, according to multiple sources, appears to be intentionally designed to operate in plain sight with just enough paperwork to pass basic scrutiny but not enough to trigger meaningful enforcement. There is no indication that regulatory bodies including customs, port health officers, or environmental oversight panels have conducted full inspections of any of the sanctioned vessels listed. Most were reportedly cleared and dismantled within days of arrival.

Rahul Mistry said: “This isn’t merely a loophole; it’s reportedly a business model. Best Oasis and Priya Blue are allegedly running a high-volume, low-visibility operation that filters sanctioned, end-of-life ships through legal instruments to appear legitimate on paper. This reportedly involves routing untaxed funds and shielded actors through a well-connected political and industrial network. As global scrutiny of ESG practices intensifies, many of these activities are allegedly being whitewashed through new partnerships and branding, but the underlying mechanisms reportedly remain unchanged.”